ALBERT

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 490〈/p〉 〈p〉Author(s): Ram Kumar, Jyoti Sharma, Kartik K. Iyer, E.V. Sampathkumaran〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We report temperature (〈em〉T〈/em〉) dependence (2–300 K) of DC and AC magnetization (〈em〉M〈/em〉), isothermal remnant magnetization (〈em〉M〈sub〉IRM〈/sub〉〈/em〉), heat-capacity (〈em〉C〈/em〉), electrical resistivity (ρ), and magnetoresistance (MR) of a ternary intermetallic compound, Gd〈sub〉4〈/sub〉PtAl, crystallizing in a cubic (space group 〈em〉F〈/em〉〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mrow〉〈mover〉〈mn〉4〈/mn〉〈mo〉-〈/mo〉〈/mover〉〈/mrow〉〈/math〉3〈em〉m〈/em〉) structure. In this structure, there are three sites for the rare-earth. The magnetization data reveal that, in addition to a magnetic transition at 64 K, there is another magnetic feature below 20 K. The 〈em〉C〈/em〉(〈em〉T〈/em〉) data reveal an upturn below 64 K, shifting to a lower temperature with increasing field, which establishes that the onset of magnetic order is of an antiferromagnetic type. However, there is no worthwhile feature near 20 K in the 〈em〉C(T)〈/em〉 curve. Ac susceptibility peak undergoes an observable change with frequency and, in particular the peak around 20 K gets suppressed with the application of a dc magnetic field; in addition, 〈em〉M〈sub〉IRM〈/sub〉〈/em〉 undergoes a slow decay with time and isothermal 〈em〉M〈/em〉 exhibits low-field hysteresis below 20 K only, which are typical of spin-glasses. The results overall suggest that this compound is a reentrant spin-glass in zero field. There are experimental signatures pointing to the existence of both antiferromagnetic and ferromagnetic components, competing with the variation of temperature and magnetic field, as a result of which electrical and magnetoresistance behaviors are peculiar. The results overall suggest that this compound exhibits interesting magnetic and transport properties.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 490〈/p〉 〈p〉Author(s): N. Leuning, S. Steentjes, M. Heller, S. Korte-Kerzel, K. Hameyer〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In material models for the finite-element simulation of electrical machines and the preceding magnetic measurements, the magnetic anisotropy of non-grain oriented electrical steel is usually considered in an oversimplified way, if at all. The magnetization behavior between rolling and transverse direction is not linear and varies with magnetic polarization, a relation that comes in addition to the complexity of the effect. In this paper, the magnetization anisotropy of five industrial non-grain oriented electrical steels is measured with a 1-D single-sheet-tester. The results are evaluated and correlated to the crystallographic texture of the studied materials. An approach to model magnetization curves at 50 Hz in arbitrary directions of the sheet plane is presented. The model is parametrized by measured magnetization curves along three different spatial directions and by macro-texture data in form of an orientation distribution function. This approach leads to a model that replicates the crossing of magnetization curves of different orientations with adequate quantitative accuracy for the application in FE magnetic field simulations.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 490〈/p〉 〈p〉Author(s): E. Saavedra, J. Escrig, J.L. Palma〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The magnetization reversal process of interconnected pentagonal spin ice systems was investigated using micromagnetic simulations and experimental measurements. Five different systems were investigated, beginning with the interconnected Shakti lattice and introducing deformations with the idea of obtaining pentagonal tiling (belonging to the P4 group) until reaching an interconnected square lattice. In all pentagonal lattices, ferromagnetic domains are pinned, acting as isolated domains in an antiferromagnetic lattice, with Cairo tiling being the lattice that allows pinning more domains. Experimental measurements on a Cairo lattice of larger dimensions show that the shape of the hysteresis curve is invariant to the size of the bars that make up the interconnected pentagonal spin ice systems.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 European Polymer Journal, Volume 118〈/p〉 〈p〉Author(s): Payam Mokhtari, Mehrorang Ghaedi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, facile and green method for synthesis of imprinted material was introduced which subsequently applied for efficient delivery of Riboflavin (vitamin B〈sub〉2〈/sub〉). Characterization of the prepared polymer was carried out by the Fourier Transform Infrared (FT-IR) spectroscopy and Scanning Electron Microscopy (SEM). The weight ratio of functional monomer to template over 5–20 W/W% was evaluated in order to find the best loading condition and subsequent release into synthetic biomimetic media namely simulated body fluid (SBF) and media including 1% NaCl solution, simulated gastric fluid (SGF) solution at pH 1.5 and the solution of 1% W/W Na〈sub〉2〈/sub〉SO〈sub〉4〈/sub〉. Under optimized condition, the highest value of released riboflavin was achieved at 1:20 ratio of riboflavin to polymer in NaCl (55.07%) media which providing that the body requirement about 5 days of this vitamin between minimum effective concentration (MEC) and maximum safe concentration (MSC) of Riboflavin in short release time (45 min). Moreover, the experimental data were fitted to Higuchi model in order to calculate Higuchi solubility constant.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S001430571930518X-ga1.jpg" width="367" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 European Polymer Journal, Volume 118〈/p〉 〈p〉Author(s): Marcin Mackiewicz, Jan Romanski, Pamela Krug, Maciej Mazur, Zbigniew Stojek, Marcin Karbarz〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Nanogels are promising carriers for drug delivery, especially when they degrade under conditions typical for cancer cells to release a drug. By using the precipitation polymerization we synthesized a biocompatible and degradable nanogel based on poly(ethylene glycol) methyl ether methacrylate (OEGMA) and di(ethylene glycol) methyl ether methacrylate (MEO〈sub〉2〈/sub〉MA) cross-linked with a redox-sensitive linker, 〈em〉N,N′〈/em〉-bis(methacryloyl)cystine – (mBISS). The application of appropriate proportions of monomers during the nanogel synthesis allowed us to set its volume-phase-transition temperature to the body temperature while the aggregation of the nanogel in physiological conditions was eliminated. The presence of carboxylic groups in mBISS made the nanogel sensitive to pH, gave it stability under conditions of high ionic strength and allowed it to bind the anticancer drug – doxorubicin (DOX). The degradation of nanogel was examined by using electron microscopies. In the presence of a high concentration of glutathione (a reducing agent for the -S-S- bridges) which is the case for most cancer cells, the spherical shape of the nanogel and correspondingly its structure were destroyed. The obtained profiles for the release of DOX from the nanogel revealed that the smallest amount of DOX was released from the nanogel at pH 7.4, while under conditions present in most cancer cells, this is at pH 5.0 and c〈sub〉GSH〈/sub〉 = 40 mM, the highest cumulative release of DOX was observed. The DOX loaded nanogels were cytotoxic against MCF-27 and HT-29 cancer cells similarly to DOX alone. The unloaded gel nanoparticles did not inhibit proliferation of the cells.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0014305719306299-ga1.jpg" width="498" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 European Polymer Journal, Volume 118〈/p〉 〈p〉Author(s): Andrea Dodero, Lara Pianella, Silvia Vicini, Marina Alloisio, Massimo Ottonelli, Maila Castellano〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Alginate-based hydrogels can be obtained by the simple addition of bivalent ions to aqueous polysaccharide solutions without the use of toxic chemicals; however, the hydrogels prepared by this way result inhomogeneous and irreproducible due to the extremely fast crosslinking reaction. To overcome such limitations, in the present work a novel preparation approach is proposed and optimized; the method is based on the use of agar moulds rich of bivalent ions as diffusing system to modulate the release of Ca〈sup〉2+〈/sup〉, Sr〈sup〉2+〈/sup〉, and Ba〈sup〉2+〈/sup〉 cations in order to guarantee a better control of the crosslinking process. A full factorial experimental design was applied to assess the effects and the mutual interactions of three selected parameters (sodium alginate concentration, crosslinking agent concentration within the agar moulds, crosslinking time) on the gelation process. The swelling and mechanical properties of the prepared hydrogels were investigated both in deionized water and in a saline environment; furthermore, the hydrogels were characterized by means of thermogravimetric analysis and field-emission scanning electron microscopy. The obtained results demonstrated that both the experimental variables and the environmental conditions have a significant influence on the structure and the performances of the resulting hydrogels. In particular, the use of high polymer concentration and crosslinking agent amount leads to strong hydrogels corresponding to a superior crosslinking degree; more in detail, Ba〈sup〉2+〈/sup〉 ions show a great affinity for alginate leading to the hydrogels with the highest mechanical properties. Moreover, the ion-exchange occurring in saline environment seems to strongly reduce the effective crosslinking degree of alginate hydrogels with a consequential loss of mechanical properties and stability. The collected data were finally elaborated through statistical analysis combined with response surface methodology to develop theoretical models successfully able to correlate the crosslinking degree to the experimental conditions, thus opening the way of designing and fabricating alginate-based hydrogels with tailored morphology and mechanical properties.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0014305719306986-ga1.jpg" width="370" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 490〈/p〉 〈p〉Author(s): H.X. Zeng, Q.X. Wang, J.S. Zhang, X.F. Liao, X.C. Zhong, H.Y. Yu, Z.W. Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Different from many previous reports, La-Al-Cu alloys with different Al/Cu ratios containing only high abundant rare earth element La were employed for grain boundary diffusion treatment for sintered NdFeB permanent magnets. It is found that Al and Cu contents should be optimized to achieve coercivity enhancement. The coercivity of the magnet was enhanced from 1000 to 1006, 1077 and 1156 kA/m after La〈sub〉70〈/sub〉Al〈sub〉10〈/sub〉Cu〈sub〉20〈/sub〉, La〈sub〉70〈/sub〉Al〈sub〉15〈/sub〉Cu〈sub〉15〈/sub〉 and La〈sub〉70〈/sub〉Al〈sub〉20〈/sub〉Cu〈sub〉10〈/sub〉 alloys diffusion, at 800 °C for 1 h followed by 500 °C for 3 h. The coercivity stability was also improved, indicated by the enhanced temperature coefficient of β from −0.63 to −0.61, −0.61 and −0.60%/K. Microstructure investigation indicates that the formation of continuous grain boundary phase after diffusion reduces the magnetic exchange interaction and contributes to the enhanced coercivity. After diffusion, the La〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 phase was observed in both the triple junction and strip grain boundary. La, Al and Cu elements showed different distributions in the magnets. The diffusion coefficients obtained from Fick’s second law indicate that La diffuses faster than Al and Cu at 800 °C, which explains the various effects of the diffusion sources and different coercivity enhancements by the alloys with different Al/Cu ratios. Although the process should be further optimized, the current results demonstrate that the grain boundary diffusion using low cost La-Al-Cu alloys can improve the microstructure and enhance the coercivity of NdFeB magnets.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 22 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials〈/p〉 〈p〉Author(s): Chang-Wei Wu, Dao-Xin Yao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Two-dimensional (2D) ferromagnetic semiconductors with robust magnetism are urgently desired for nanoscale spintronics applications. However, it remains a challenge to realize them experimentally. In this work, we proposed intriguing 2D p-orbital ferromagnetic semiconductors 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si29.svg"〉〈mrow〉〈msub〉〈mrow〉〈mi mathvariant="normal"〉X〈/mi〉〈/mrow〉〈mrow〉〈mn〉2〈/mn〉〈/mrow〉〈/msub〉〈msub〉〈mrow〉〈mi mathvariant="normal"〉NO〈/mi〉〈/mrow〉〈mrow〉〈mn〉2〈/mn〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 (〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si30.svg"〉〈mrow〉〈mi〉X〈/mi〉〈mo〉=〈/mo〉〈mi mathvariant="italic"〉Ca〈/mi〉〈mo〉,〈/mo〉〈mi mathvariant="italic"〉Sr〈/mi〉〈/mrow〉〈/math〉) monolayer with 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si31.svg"〉〈mrow〉〈mn〉3〈/mn〉〈msub〉〈mrow〉〈mi〉μ〈/mi〉〈/mrow〉〈mrow〉〈mi〉B〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 magnet per unit under O surface termination using first-principles calculations. The 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si32.svg"〉〈mrow〉〈msub〉〈mrow〉〈mi mathvariant="normal"〉Ca〈/mi〉〈/mrow〉〈mrow〉〈mn〉2〈/mn〉〈/mrow〉〈/msub〉〈msub〉〈mrow〉〈mi mathvariant="normal"〉NO〈/mi〉〈/mrow〉〈mrow〉〈mn〉2〈/mn〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 monolayer is bipolar magnetic material (BMS) with spin-flip gap 0.24 eV, and the 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si33.svg"〉〈mrow〉〈msub〉〈mrow〉〈mi mathvariant="normal"〉Sr〈/mi〉〈/mrow〉〈mrow〉〈mn〉2〈/mn〉〈/mrow〉〈/msub〉〈msub〉〈mrow〉〈mi mathvariant="normal"〉NO〈/mi〉〈/mrow〉〈mrow〉〈mn〉2〈/mn〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 is half-semiconductor (HSC) with spin-flip gap 0.31 eV, which is large enough to prevent the spin-flip transition. The Curie temperature can reach to 206 and 239 K, respectively, due to the superexchange interaction between 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si34.svg"〉〈mrow〉〈msup〉〈mrow〉〈mi〉N〈/mi〉〈/mrow〉〈mrow〉〈mo〉-〈/mo〉〈/mrow〉〈/msup〉〈/mrow〉〈/math〉 ions. The values are much higher than the boiling point of liquid nitrogen (77 K) and comparable to that of the reported 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si35.svg"〉〈mrow〉〈mi mathvariant="normal"〉ScCl〈/mi〉〈/mrow〉〈/math〉 monolayer. Moreover, the half metals are obtained via carrier doping for both the 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si36.svg"〉〈mrow〉〈msub〉〈mrow〉〈mi mathvariant="normal"〉Ca〈/mi〉〈/mrow〉〈mrow〉〈mn〉2〈/mn〉〈/mrow〉〈/msub〉〈msub〉〈mrow〉〈mi mathvariant="normal"〉NO〈/mi〉〈/mrow〉〈mrow〉〈mn〉2〈/mn〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 and 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si37.svg"〉〈mrow〉〈msub〉〈mrow〉〈mi mathvariant="normal"〉Sr〈/mi〉〈/mrow〉〈mrow〉〈mn〉2〈/mn〉〈/mrow〉〈/msub〉〈msub〉〈mrow〉〈mi mathvariant="normal"〉NO〈/mi〉〈/mrow〉〈mrow〉〈mn〉2〈/mn〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 monolayers. In addition, the half-metallic completely spin-polarized direction of BMS 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si38.svg"〉〈mrow〉〈msub〉〈mrow〉〈mi mathvariant="normal"〉Ca〈/mi〉〈/mrow〉〈mrow〉〈mn〉2〈/mn〉〈/mrow〉〈/msub〉〈msub〉〈mrow〉〈mi mathvariant="normal"〉NO〈/mi〉〈/mrow〉〈mrow〉〈mn〉2〈/mn〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 monolayer can be controlled by carrier doping type. Furthermore, the magnetism of 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si39.svg"〉〈mrow〉〈msub〉〈mrow〉〈mi mathvariant="normal"〉X〈/mi〉〈/mrow〉〈mrow〉〈mn〉2〈/mn〉〈/mrow〉〈/msub〉〈msub〉〈mrow〉〈mi mathvariant="normal"〉NO〈/mi〉〈/mrow〉〈mrow〉〈mn〉2〈/mn〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 monolayer is derived from p orbital, without the involvement of conventional transition metals or rare earth atoms. This is advantageous for high-speed and long-distance spin-polarization transport. These results suggest that the 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si40.svg"〉〈mrow〉〈msub〉〈mrow〉〈mi mathvariant="normal"〉X〈/mi〉〈/mrow〉〈mrow〉〈mn〉2〈/mn〉〈/mrow〉〈/msub〉〈msub〉〈mrow〉〈mi mathvariant="normal"〉NO〈/mi〉〈/mrow〉〈mrow〉〈mn〉2〈/mn〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 monolayer can develop spin field effect transistor for information processing and storage, and open opportunities for designing new ferromagnetic semiconductors.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0304885319322772-ga1.jpg" width="160" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 European Polymer Journal, Volume 119〈/p〉 〈p〉Author(s): Maria Toplishek, Ema Žagar, David Pahovnik〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A synthetic approach to the dicyano-substituted ε-caprolactone was developed. It consists of a cyclohexanone ring assembly through the Diels-Alder reaction followed by the Baeyer-Villiger oxidation. Ring-opening polymerization of the synthesized monomer, catalyzed by the aluminum alkoxides, was performed in a well-controlled manner and provided the nitrile-polyester homopolymers of various molar masses. The synthesized nitrilePCL homopolymers are amorphous with a significantly higher glass transition temperature (66–69 °C) compared to the unsubstituted PCL. The dicyano-substituted ε-caprolactone monomer was copolymerized with the unsubstituted ε-caprolactone to prepare the statistical and block copolymers. Furthermore, the cyano groups of the nitrilePCL homopolymers were transformed into the amide groups by post-polymerization modification under anhydrous conditions using the Wilkinson’s catalyst. The resulting amide-functionalized polyesters are water-soluble when the degree of transformation is higher than 80%.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S001430571931225X-ga1.jpg" width="339" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 European Polymer Journal, Volume 119〈/p〉 〈p〉Author(s): Ander Reizabal, José Manuel Laza, José María Cuevas, Luis Manuel León, José Luis Vilas-Vilela〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Different polycyclooctene (PCO) and linear low-density polyethylene (LLDPE) blends were crosslinked with 2 wt% of dicumyl peroxide (DCP) in order to obtain thermoresponsive shape memory materials with transition temperatures close to bodýs external temperature. These polymeric blends allow tailoring properties by the synergic combination of shape-memory capability of PCO and effective mechanical and processing performance of polyethylene. Thermal stability of these materials was characterised by thermogravimetric analysis (TGA), whereas mechanical performance was measured by dynamic mechanical analysis (DMA) and tensile tests. Besides, thermal properties were measured by differential scanning calorimetry (DSC), where the melting temperature of crystalline PCO phase around 40–50 °C were observed. Considering this shape memory triggering temperature, the shape memory capabilities of the samples were studied by thermo-mechanical analysis (TMA), and outstanding shape recovery ratios were obtained. Finally, water contact angle (WCA) and water vapour transmission rate (WVTR) were measured above and below that transition temperature to assess moisture permeability changes. In this case, observed increase by an order of magnitude in vapour permeability with temperature offers promising opportunities in developing thermo-active membranes for textile applications with these PCO-LLDPE blends.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0014305719309899-ga1.jpg" width="365" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 493〈/p〉 〈p〉Author(s): Chicheng Ma, Kai Liu, Xingqi Han, Sheng Yang, Nan Ye, Jiancheng Tang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The martensitic transformation (MT) and magnetocaloric properties are investigated in melt-spun Mn〈sub〉50〈/sub〉Ni〈sub〉31.5〈/sub〉Co〈sub〉8.5〈/sub〉Ti〈sub〉10〈/sub〉 all-3〈em〉d〈/em〉-metal alloy ribbons fabricated at different wheel speeds (WSs), 15, 20, and 25 m/s. All these ribbon samples reveal a coexistence of the predominant 5-layer modulated (5 M) (monoclinic, space group 〈em〉P〈/em〉2/〈em〉m〈/em〉) martensite and a small amount of non-modulated (NM) 〈em〉L〈/em〉1〈sub〉0〈/sub〉 structure (tetragonal, space group 〈em〉P〈/em〉4/〈em〉mmm〈/em〉) martensite at room temperature (RT), implying the MT temperature is above RT. With the increase of WSs from 15 to 25 m/s, the structural and magnetic parameters, such as average grain size, unit cell volume, MT temperature, and magnetic entropy change, decrease. However, it is worth noting that from 20 to 25 m/s, the reduction becomes much more sluggish or even almost stagnate in comparison with that from 15 to 20 m/s. Large effective refrigeration capacity ~79.4 J kg〈sup〉−1〈/sup〉 is obtained in sample with 20 m/s under 〈em〉μ〈/em〉〈sub〉0〈/sub〉Δ〈em〉H〈/em〉 = 0–5 T, indicating that these ribbons could be the potential candidate for magnetic refrigeration. The origins of manipulation in MT by WSs in these ribbon samples are discussed.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 493〈/p〉 〈p〉Author(s): Xiao Zhou, Ruirui Liu, Haitao Zhou〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The microstructures and soft magnetic properties of Co〈sub〉66〈/sub〉Fe〈sub〉4〈/sub〉Mo〈sub〉2〈/sub〉Si〈sub〉16〈/sub〉B〈sub〉12〈/sub〉 amorphous tape wound core were systematically investigated. The phase composition and corresponding structure evaluation of Co〈sub〉66〈/sub〉Fe〈sub〉4〈/sub〉Mo〈sub〉2〈/sub〉Si〈sub〉16〈/sub〉B〈sub〉12〈/sub〉 amorphous ribbon after annealing at various temperatures were identified firstly. In particular, at 758 K the microstructure of the ribbon is primarily composed of Co〈sub〉2〈/sub〉B, Fe〈sub〉2〈/sub〉B and β-Co phases. With the temperature approaching to 768 K, the new phases α-Co and CoSi appears. When the temperature increases to 778 K, the mixed phase combination of α(Co) + β(Co) + Co〈sub〉2〈/sub〉B + Fe〈sub〉2〈/sub〉B + CoSi exists along with an apparent nano-crystallization. The soft magnetic properties of tape wound core assembled by Co〈sub〉66〈/sub〉Fe〈sub〉4〈/sub〉Mo〈sub〉2〈/sub〉Si〈sub〉16〈/sub〉B〈sub〉12〈/sub〉 amorphous ribbon were then studied at annealed temperature from 713 K to 753 K. At 723 K, we found the permeability is highest with a maximum value of 〈em〉μ〈sub〉m〈/sub〉〈/em〉 = 1.675 × 10〈sup〉3〈/sup〉, and the coercive force is lowest with a minimum value of 0.134 Oe. The magnetization curve and the hysteresis loop of established tape would core annealed at 713–753 K remain almost unchanged. Finally, the relation between frequency and magnetic permeability and quality factor were carefully examined at different annealing temperatures.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 21 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials〈/p〉 〈p〉Author(s): Rihab Jabbar, Sabah H. Sabeeh, Awham M. Hameed〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Manganese (Mn〈sup〉+2〈/sup〉) doped spinel cobalt ferrites nanoparticles (NPs) having composition (Mn〈sub〉x〈/sub〉Co〈sub〉1-x〈/sub〉Fe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 where x = 0.2, 0.4, 0.6 and 0.8) were synthesized by sol-gel precipitation method. The structural, dielectric and magnetic properties were characterized via X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), LCR meter, and vibrating sample magnetometer (VSM). The average crystallite size (D) was found to increase from 10.79 nm to 14.18 nm with increasing the Mn〈sup〉+2〈/sup〉 doping ratio from (0.2 to 0.6) then decrease to 9.95 nm with further increasing of Mn〈sup〉+2〈/sup〉 to (0.8). FTIR spectrum confirmed the formation of the spinal structure of ferrite, where the main observed bands (416.64 – 459.07 cm〈sup〉-1〈/sup〉) assigned to the octahedral complexes and (513.08 – 574.81 cm〈sup〉-1〈/sup〉) assigned to tetrahedral complexes. The dielectric properties of samples found to be decreased with increasing the doping ratio. While the hysteresis loop obtains from VSM indicated the formation of soft magnetic material and the saturation magnetization decrease from 56 emu g〈sup〉-1〈/sup〉 (Mn〈sup〉+2〈/sup〉 = 0.2) to 38 emu g〈sup〉-1〈/sup〉 (Mn〈sup〉+2〈/sup〉 = 0.8).〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 European Polymer Journal, Volume 119〈/p〉 〈p〉Author(s): Busra Tugce Duymaz, Fatma Betul Erdiler, Tugba Alan, Mehmet Onur Aydogdu, Ahmet Talat Inan, Nazmi Ekren, Muhammet Uzun, Yesim Muge Sahin, Erdi Bulus, Faik Nüzhet Oktar, Sinem Selvin Selvi, Ebru ToksoyOner, Osman Kilic, Muge Sennaroglu Bostan, Mehmet Sayip Eroglu, Oguzhan Gunduz〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Poly(ε-caprolactone) (PCL), gelatin (GT) and different concentrations of low molecular weight 〈em〉Halomonas〈/em〉 levan (HLh) were combined and examined to develop physical networks serving as tissue scaffolds to promote cell adhesion for biocompatibility. Three-dimensional bioprinting technique (3D bioprinting) was employed during manufacturing the test samples and their comprehensive characterization was performed to investigate the physicochemical properties and biocompatibility. Physical properties of the printing materials such as viscosity, surface tension, and density were measured to determine optimal parameters for 3D bioprinting. The scanning electron microscope (SEM) was used to observe the morphological structure of scaffolds. Fourier-Transform Infrared Spectroscopy (FT-IR) and differential scanning calorimetry (DSC) were used to identify the interactions between the components. 〈em〉In-vitro〈/em〉 cell culture assays using standard human osteoblast (Hob) cells showed increased biocompatibility of the printing materials with increasing HLh content. Thus, the formulations including the HLh are expected to be a good candidate for the production of 3D printed materials.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0014305719313862-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 European Polymer Journal, Volume 119〈/p〉 〈p〉Author(s): Maria A. Murcia Valderrama, Robert-Jan van Putten, Gert-Jan M. Gruter〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Plastic materials are indispensable in everyday life because of their versatility, high durability, lightness and cost-effectiveness. As a consequence, worldwide plastic consumption will continue to grow from around 350 million metric tons per annum today to an estimated 1 billion metric tons per annum in 2050. For applications where polymers are applied in the environment or for applications where polymers have a bigger chance of ending up in the environment, (bio)degradable polymers need to be developed to stop endless accumulation of non-degradable polymers irreversibly littering our planet.〈/p〉 〈p〉As monomers and polymers represent more than 80% of the chemical industry’s total production volume, a transition from fossil feedstock today (99% of the current feedstock for polymers is fossil-based) to a significantly larger percentage of renewable feedstock in the future (carbon that is already “above the ground”) will be required to meet the greenhouse gas reduction targets of the Paris Agreement (〉80% CO〈sub〉2〈/sub〉 reduction target for the European Chemical Industry sector in 2050).〈/p〉 〈p〉The combination of the predicted polymer market growth and the emergence of new feedstocks creates a fantastic opportunity for novel sustainable polymers. To replace fossil based feedstock, there are only three sustainable alternative sources: biomass, CO〈sub〉2〈/sub〉 and existing plastics (via recycling). The ultimate circular feedstock would be CO〈sub〉2〈/sub〉: it can be electrochemically reduced to formic acid derivatives that can subsequently be converted into useful monomers such as glycolic acid and oxalic acid. In order to assess the future potential for these polyester building blocks, we will review the current field of polyesters based on these two monomers. Representative synthesis methods, general properties, general degradation mechanisms, and recent applications will be discussed in this review. The application potential of these polyesters for a wide range of purposes, as a function of production cost, will also be assessed. It is important to note that polymers derived from CO〈sub〉2〈/sub〉 do not necessarily always lead to lower net overall CO〈sub〉2〈/sub〉 emissions (during production of after use, e.g. degradation in landfills). This needs to be evaluated using robust LCA’s and this information is currently not available for the materials discussed in this review.〈/p〉 〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0014305719309164-ga1.jpg" width="260" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 European Polymer Journal, Volume 119〈/p〉 〈p〉Author(s): Kunshan Ding, Yajie Zhang, Zhihao Huang, Baolei Liu, Qiunan Shi, Lihua Hu, Nianchen Zhou, Zhengbiao Zhang, Xiulin Zhu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Digital polymers with precise arrangements of units acting as the 0- or 1-bit, have shown bright promise for the data storage media. The easiness of encoding and decoding these polymers is essential when putting them into practical applications. Herein, the concept of utilizing sequence building block and sequencing indicator to generate easily encodable and decodable digital polymers is proposed. With the thiol-maleimide Michael coupling for digital chain growth, the dithiosuccinimide (DTS) motifs generated from the succinimide thioether linkages are used as the sequence building block. The DTS can be equipped with different groups, thus greatly enabling the modular encoding process. Importantly, the tandem mass spectrometry (MS/MS) results unveil the relatively abundant DTS-induced MS signal, which facilitates the decoding process with DTS acting as the sequencing indicator. The synergetic MS/MS induced cleavages of the two C〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉S bonds on DTS are responsible for the relatively abundant MS signal. Finally, the work exemplifies the quantitatively decoding of a digital polymer with DTS as the sequence building block and sequencing indicator. This study demonstrates the concept of sequence building block and sequencing indicator, which advances the digital polymers for practical applications.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉The easily encodable and decodable digital polymer using dithiosuccinimide as sequence building block and sequencing indicator was proposed.〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0014305719310225-ga1.jpg" width="253" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 493〈/p〉 〈p〉Author(s): Yanan Zhang, Lu Li, Shunqun Liu, Diangang Pan, Lei Chen, Hong Chang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The nonmagnetic In〈sup〉3+〈/sup〉 doping in the hexagonal SrFe〈sub〉12−〈/sub〉〈em〉〈sub〉x〈/sub〉〈/em〉In〈em〉〈sub〉x〈/sub〉〈/em〉O〈sub〉19〈/sub〉 (〈em〉x〈/em〉 = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 1 and 2) permanent magnet increases the saturation magnetization at 300 K with the highest value up to 73.87 emu/g at 〈em〉x〈/em〉 = 0.5, and decreases it with 〈em〉x〈/em〉 〉 0.5. The coercive field keeps almost the same for 〈em〉x〈/em〉 ≤ 0.2, but it decreases with 〈em〉x〈/em〉 〉 0.2. The Curie temperature linearly decreases from 740 K for 〈em〉x〈/em〉 = 0 to 610 K for 〈em〉x〈/em〉 = 1.0, and decreases at a much lower rate to 592 K for 〈em〉x〈/em〉 = 2.0. The XPS, FT-IR and UV–vis spectra are carried out to characterize the relations between the magnetic properties and the structure. The In〈sup〉3+〈/sup〉 ions preferentially occupy the tetragonal 4f1 site, deduced from the xrd refinement and the FT-IR spectra. It is consistent with the increasing magnetization by the In〈sup〉3+〈/sup〉 doping. Oxygen vacancies exist in the compounds. The In〈sup〉3+〈/sup〉 doping and oxygen vacancies deteriorate the coercivity, while Fe〈sup〉2+〈/sup〉 ions are in favor of a high magnetocrystalline anisotropy. The energy band gap of SrFe〈sub〉12−〈/sub〉〈em〉〈sub〉x〈/sub〉〈/em〉In〈em〉〈sub〉x〈/sub〉〈/em〉O〈sub〉19〈/sub〉 increases with the increasing In〈sup〉3+〈/sup〉 doping from 1.75 eV for 〈em〉x〈/em〉 = 0 to 1.87 eV for 〈em〉x〈/em〉 = 1.0, but that of 〈em〉x〈/em〉 = 2.0 decreases to 1.79 eV. It reflects that oxygen vacancies in 〈em〉x〈/em〉 = 2.0 play a function on the energy band gap.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 493〈/p〉 〈p〉Author(s): D.A. Petrov, R.D. Ivantsov, S.M. Zharkov, D.A. Velikanov, M.S. Molokeev, C.-R. Lin, C.-T. Tso, H.-S. Hsu, Y.-T. Tseng, E.-S. Lin, I.S. Edelman〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Effect of Ag inclusions on magnetic properties and magnetic circular dichroism (MCD) of Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 nanoparticles (NPs) in the mixed system of Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 and Ag NPs in dependence on the relative concentration of the components is presented. The samples were synthesized by the thermal decomposition of the mixture of constant concentration of Fe(NO〈sub〉3〈/sub〉)〈sub〉3〈/sub〉·9H〈sub〉2〈/sub〉O and varied concentration of AgNO〈sub〉3〈/sub〉. The synthesized powdered samples consisted of Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 and Ag NPs located very close with each other, and in the most cases the Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 NPs were bordered with the Ag nanocrystals. The Ag introducing in the samples does not effect, practically, in the Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 NPs morphology and size distribution. At the same time, Ag NPs in the powdered samples cause a decrease in the Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 NPs magnetization and shift of the blocking temperature to lower temperatures, both approximately proportional to the Ag concentration. Most significant changes are revealed in the MCD spectra in the energy region of 1.2–2.2 eV. We have discussed the influence of the Ag NPs on the MCD spectra features in terms of the charge-transfer electron transitions.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 21 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials〈/p〉 〈p〉Author(s): Sanae Zriouel〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Based on our works [1], [2], [3], [4], we report the magnetic and hysteretic properties of graphene-based Janus materials namely, pure and doped zigzag graphone nanoribbons, hexagonal core/shell graphene-like nanoribbon, and graphyne core/shell nanoparticle, within the framework of both Monte Carlo calculations and mean field theory. We have reported the effects of the Hamiltonian parameters on the magnetic and the thermodynamic quantities of the systems. The total magnetization, the susceptibility, the specific heat, and the hysteresis curves, as well as the critical temperature and the compensation behavior, that is of crucial importance for technological applications such as thermo-optical recording, are studied. A number of characteristic behaviors are found, such as the existence of two new and non-classified magnetization profiles in addition to the 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si80.svg"〉〈mrow〉〈mi〉Q〈/mi〉〈mo〉-〈/mo〉〈mo〉,〈/mo〉〈mi〉P〈/mi〉〈mo〉-〈/mo〉〈/mrow〉〈/math〉, and 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si81.svg"〉〈mrow〉〈mi〉N〈/mi〉〈mo〉-〈/mo〉〈/mrow〉〈/math〉types of compensation behavior and the occurrence of square, single, and triple hysteresis loops which exhibit different step effects and various shapes.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 22 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials〈/p〉 〈p〉Author(s): M. Zarifi, P. Kameli, T. Raoufi, A. Ghotbi Varzaneh, D. Salazar, M.I. Nouraddini, L. Kotsedi, M. Maaza〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The magnetocaloric properties in La〈sub〉0.5〈/sub〉Ca〈sub〉0.5-x〈/sub〉Pb〈sub〉x〈/sub〉MnO〈sub〉3〈/sub〉 (0≤x≤0.2) manganites are considered by both direct and indirect measurement techniques. The ac susceptibility shows that the compounds with low Pb doping exhibit mixture of CE-type AFM ordering and FM phase, while at high Pb doping FM phase is dominated. For samples x=0 and 0.05, the M-H curves at different temperatures exhibit the magnetization first increases and then decreases with decreasing temperature, indicating the growth of the AFM phase below T〈sub〉N〈/sub〉. In the curves for samples x=0.1 and 0.2, with decreasing temperature the magnetization increases and the FM phase is overcoming at low temperature. The magnetic entropy change (ΔS〈sub〉M〈/sub〉) is enhanced continuously with increasing Pb concentration up to x=0.1, then slightly decreases. The magnetocaloric effect in the vicinity of T〈sub〉C〈/sub〉 for x= 0.1 and 0.2 was investigated by the direct field-induced adiabatic temperature change (ΔT〈sub〉ad〈/sub〉). The results of the direct method show the absolute values of obtained ΔT〈sub〉ad〈/sub〉 are almost the same for both samples (0.62 and 0.53 K under 1.96 T for x=0.1 and 0.2, respectively). The outcomes demonstrate that doping by Pb is a promising material for the magnetic refrigeration.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 493〈/p〉 〈p〉Author(s): Shabir Ahmad Mir, Dinesh C. Gupta〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Ba〈sub〉2〈/sub〉MUO〈sub〉6〈/sub〉 (M = Co, Ni) alloys are investigated to understand their electronic structure, magnetic character together with thermoelectric behavior using 〈em〉ab-initio〈/em〉 formulism. The variations in physical properties by changing M-site atom are analyzed. The crystal structure of Ba〈sub〉2〈/sub〉MUO〈sub〉6〈/sub〉 (M = Co, Ni) alloys is found to be face-centered cubic (〈em〉Fm-3m〈/em〉) with lattice constant of 0.845 nm for Ba〈sub〉2〈/sub〉CoUO〈sub〉6〈/sub〉 and 0.841 nm for Ba〈sub〉2〈/sub〉NiUO〈sub〉6〈/sub〉. The band structure and density of states convey half-metallic ferromagnetic character of Ba〈sub〉2〈/sub〉CoUO〈sub〉6〈/sub〉, while Ba〈sub〉2〈/sub〉NiUO〈sub〉6〈/sub〉 exhibit ferromagnetic semiconducting nature. The electron filling in the 〈em〉d〈/em〉-orbitals of Co and Ni determines the overall electronic and magnetic character of alloys. The obtained structural parameters and magnetic moment are consistent with experimental results. The variation in various thermoelectric parameters with temperature is also examined. The highest value of power factor obtained for Ba〈sub〉2〈/sub〉NiUO〈sub〉6〈/sub〉 and Ba〈sub〉2〈/sub〉CoUO〈sub〉6〈/sub〉 is 54.92 μW cm〈sup〉−1〈/sup〉 K〈sup〉−2〈/sup〉 and 9.25 μW cm〈sup〉−1〈/sup〉 K〈sup〉−2〈/sup〉, respectively. The semiconducting nature in both spin orientations favors Ba〈sub〉2〈/sub〉NiUO〈sub〉6〈/sub〉 for thermoelectric applications. The computed elastic constants along with other elastic parameters suggest that these alloys are mechanically stable and possess ductile character.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 European Polymer Journal, Volume 119〈/p〉 〈p〉Author(s): Fatemeh Zarei, Azam Marjani, Roozbeh Soltani〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉To capture heavy metals in aqueous solution, it is imperative to develop viable and safe heavy metals uptake techniques. Herein, we report polymer matrix nanocomposite adsorbents with 2 and 5 wt.% nanofiller contents based on functionalised mesoporous fibrous silica KCC-1, chitosan, and oleic acid (abbreviated as TA-KCC-1/Chi-OLA NC). TA-KCC-1/Chi-OLA NCs relying on physicochemical adsorption are potential candidates for heavy metals removal because of their facile fabrication procedure, low toxicity, biodegradability, and high affinity toward heavy metals. The adsorption of Pb(II) cations onto green TA-KCC-1/Chi-OLA 5 wt.% adsorbent was studied in the batch system. Langmuir and pseudo-second-order models were found to be the best fit models to predict isotherms and kinetics of adsorption, respectively. The maximum adsorption capacity according to the Langmuir model was 168 mg g〈sup〉−1〈/sup〉 (adsorption conditions: pH: 9.0, adsorbent dose: 20.0 mg; contact time: 100 min; initial concentration: 100 mg L〈sup〉−1〈/sup〉).〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0014305719312339-ga1.jpg" width="399" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 European Polymer Journal, Volume 119〈/p〉 〈p〉Author(s): Benjámin Gyarmati, Béla Pukánszky〈/p〉

Description: 〈p〉Publication date: September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 European Polymer Journal, Volume 118〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 1 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 493〈/p〉 〈p〉Author(s): Haitao Zhou, Desheng Pan, Yong Li, Da Li, C.J. Choi, Zhidong Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, we report the magnetic properties of metal–organic frameworks (MOF) of perovskite-like [(CH〈sub〉3〈/sub〉)〈sub〉2〈/sub〉NH〈sub〉2〈/sub〉]M(HCOO)〈sub〉3〈/sub〉 (M = Fe〈sup〉II〈/sup〉, Co〈sup〉II〈/sup〉) and niccolite-like [(CH〈sub〉3〈/sub〉)〈sub〉2〈/sub〉NH〈sub〉2〈/sub〉]Fe〈sup〉III〈/sup〉Fe〈sup〉II〈/sup〉(HCOO)〈sub〉6〈/sub〉 synthesized by a solvothermal route. The [(CH〈sub〉3〈/sub〉)〈sub〉2〈/sub〉NH〈sub〉2〈/sub〉]Fe〈sup〉II〈/sup〉(HCOO)〈sub〉3〈/sub〉 exhibits two magnetic transitions at the temperatures of ~19 K for the canted weak ferromagnetic ordering and of ~10 K for the blocking of single-ion quantum magnet due to phase separation, while the [(CH〈sub〉3〈/sub〉)〈sub〉2〈/sub〉NH〈sub〉2〈/sub〉]Co〈sup〉II〈/sup〉(HCOO)〈sub〉3〈/sub〉 shows one magnetic transition at the Curie temperature (T〈sub〉C〈/sub〉) of 14.9 K for the canted weak ferromagnetic ordering. Below the T〈sub〉C〈/sub〉 values, spin-flop transition is observed in the magnetization curves of the [(CH〈sub〉3〈/sub〉)〈sub〉2〈/sub〉NH〈sub〉2〈/sub〉]M(HCOO)〈sub〉3〈/sub〉 crystals with the critical magnetic field of about 104 kOe and 90 kOe at 10 K, respectively. Multistep-like jumping magnetization transitions induced by high magnetic field are observed in the [(CH〈sub〉3〈/sub〉)〈sub〉2〈/sub〉NH〈sub〉2〈/sub〉]Fe〈sup〉III〈/sup〉Fe〈sup〉II〈/sup〉(HCOO)〈sub〉6〈/sub〉 in a temperature range between 10 and 25 K, indicating a complex spin configuration different from that in the [(CH〈sub〉3〈/sub〉)〈sub〉2〈/sub〉NH〈sub〉2〈/sub〉]M(HCOO)〈sub〉3〈/sub〉 MOFs.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 493〈/p〉 〈p〉Author(s): B. Gokul, P. Saravanan, P. Matheswaran, M. Pandian, R. Sathyamoorthy, K. Asokan, V.T.P. Vinod, Miroslav Černík〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We herein investigate the novel magnetic interactions, such as exchange bias (EB), memory effect (ME) and magnetic relaxation dynamics (MRD) in NiO and 10 wt% Gd doped NiO nanoparticles synthesized by hydrothermal process. X-ray diffraction studies showed crystallization of face-centered-cubic structure for both NiO and Gd-doped NiO nanoparticles. Transmission electron microscopy analysis revealed a spherical morphology for both samples and their mean particle sizes were estimated as 24.5 and 10.3 nm for the pure and Gd-doped NiO nanoparticles, respectively. SQUID magnetic measurements demonstrated the occurrence of large EB coupling: 1.04 and 0.767 kOe; and enhanced coercive fields: 1.75 and 1.27 kOe, for the pure and Gd-doped NiO nanoparticles, respectively. The size-dependent magnetic properties such as, EB, ME and MRD is found to vanish at the average blocking temperature and interestingly, these properties set-in on cooling the samples at 5 K under applied field of 5 kOe. The surface defects such as oxygen vacancies and the Gd〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 impurity phase played a significant role in determining the EB and ME characteristics of NiO nanoparticles.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 493〈/p〉 〈p〉Author(s): S. Sadeghi, S.M. Hamidi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We numerically examine the role of Fano resonance for enhanced magneto-optical effect in an arrayed magneto-plasmonic core-shell structure composed of Bi:YIG cores as a magneto-optical active medium and Au sells as plasmonic ones. The optical and magneto-optical behavior of the magneto-plasmonic core-shell grating structure sustaining Fano resonance is investigated by means of Lumerical software based on the finite-difference time-domain solver. In the proposed structure, Fano resonance arises from the interplay between the guided mode and the surface plasmon resonance which results in enhanced magneto-optical Faraday effect. In addition, the Fano resonance and correspond enhanced magneto-optical effect can be tuned by changing the array period of the structure. The obtained results can be of interest in miniaturized and advanced magneto-optical devices.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 493〈/p〉 〈p〉Author(s): Muhammad Waqas〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Heat transfer in ferromagnetic stretching flow by moving surface considering a magnetic dipole is elaborated in current research. Rheological relations of non-Newtonian (Williamson) fluid are taken into account for modeling and analysis. Chemical reactions (homogeneous and heterogeneous) are considered for elaboration of mass transportation characteristics. Governing flow expressions are reduced to ODEs by implementing transformation procedure. The well-known bvp4c scheme is used for nonlinear systems computation. Influences of sundry parameters like ferrohydrodynamic interaction parameter, Weissenberg number, homogeneous-heterogeneous reaction parameters, Prandtl number and heat generation parameter on velocity, thermal and solutal fields in addition to coefficient of skin-friction and Nusselt number are displayed via graphs and tabular values. It is revealed that velocity and thermal fields have opposite behavior for ferrohydrodynamic interaction parameter. Besides the heat transportation rate is improved subjected to larger Prandtl number.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 492〈/p〉 〈p〉Author(s): Viktor Ivashko, Oleg Angelsky, Petro Maksimyak〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Ferromagnetism of nano-graphene layer within Ising model was studied. All results were obtained by using Monte Carlo simulation based on Metropolis algorithm. By applying external magnetic field at room temperature, a gradual transition between ferromagnetic and paramagnetic phases was obtained. This indicates to a potentiality of such a monolayer to be used as a magnetic field sensor. The existence of hysteresis, was established, which strongly depends on the type and magnitude of the interaction strength between the nearest neighbor lattice nodes (spins). Gradual two-step transition between ferromagnetic and paramagnetic phases near absolute zero temperature, was obtained. The results of numerical simulations are in agreement with the available experimental works of other authors.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 493〈/p〉 〈p〉Author(s): L.S. Paixão, G. Rangel, E.O. Usuda, W. Imamura, J.C.G. Tedesco, J.C. Patiño, A.M. Gomes, C.S. Alves, A.M.G. Carvalho〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Since the discovery of the giant magnetocaloric effect in the compound Gd〈sub〉5〈/sub〉Si〈sub〉2〈/sub〉Ge〈sub〉2〈/sub〉, rare earth based intermetallics of the form R〈sub〉5〈/sub〉(Si,Ge)〈sub〉4〈/sub〉 have been largely investigated in their structural and magnetic properties. From the parent compounds Gd〈sub〉5〈/sub〉Si〈sub〉4〈/sub〉 and Nd〈sub〉5〈/sub〉Si〈sub〉4〈/sub〉, the present paper reports the magnetic and magnetocaloric properties of the series 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si23.svg"〉〈mrow〉〈msub〉〈mrow〉〈mi mathvariant="normal"〉Gd〈/mi〉〈/mrow〉〈mrow〉〈mn〉5〈/mn〉〈mo〉-〈/mo〉〈mi〉x〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si24.svg"〉〈mrow〉〈msub〉〈mrow〉〈mi mathvariant="normal"〉Nd〈/mi〉〈/mrow〉〈mrow〉〈mi〉x〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉Si〈sub〉4〈/sub〉. Our results indicate that the magnetic moments of the Gd and Nd sublattices are antiparallel, where the moment of each sublattice has almost the same magnitude near 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si25.svg"〉〈mrow〉〈mi〉x〈/mi〉〈mo linebreak="goodbreak" linebreakstyle="after"〉=〈/mo〉〈mn〉4〈/mn〉〈/mrow〉〈/math〉. The antiparallel alignment of the sublattices is detrimental to the magnetocaloric properties of the samples. The end members of the series present larger entropy changes, while for the compound 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si26.svg"〉〈mrow〉〈mi〉x〈/mi〉〈mo linebreak="goodbreak" linebreakstyle="after"〉=〈/mo〉〈mn〉4〈/mn〉〈/mrow〉〈/math〉 such quantity is much lower when compared to all other samples.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 493〈/p〉 〈p〉Author(s): P. Lampen-Kelley, E.M. Clements, B. Casas, M.H. Phan, H. Srikanth, J. Marcin, I. Skorvanek, H.T. Yi, S.W. Cheong〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We have recently applied the magnetic field and temperature dependence of magnetic entropy change as a probe of the magnetic states of a single crystal of Ca〈sub〉3〈/sub〉Co〈sub〉2〈/sub〉O〈sub〉6〈/sub〉 to establish a more comprehensive magnetic phase diagram for this exotic system. The results are consistent with the spin-density wave description of the ground state and indicate the suppression of the modulated state in favor of a ferrimagnetic up-up-down arrangement of the spin chains with the application of a moderate field. We demonstrate, in this study, that the features of the static magnetic phase diagram are preserved when the grain size of Ca〈sub〉3〈/sub〉Co〈sub〉2〈/sub〉O〈sub〉6〈/sub〉 is reduced to 440 nm (below the maximum 〈em〉c〈/em〉-axis correlation length of ~550 nm in Ca〈sub〉3〈/sub〉Co〈sub〉2〈/sub〉O〈sub〉6〈/sub〉), although the polycrystalline materials show a non-saturating behavior, rounded steps, and reduced magnetization when compared to the single crystal. Our new finding of the multiple low-temperature magnetization steps in the 440 nm sample, together with conflicting reports concerning such steps in nanostructured samples, suggests that correlations in the 〈em〉ab〈/em〉 plane are more important than correlations along the 〈em〉c〈/em〉-axis in the appearance of the plateaus. The relaxation processes in the system are studied through the decay of remanent magnetization, ac susceptibility, and Argand diagrams. The introduction of grain boundaries in Ca〈sub〉3〈/sub〉Co〈sub〉2〈/sub〉O〈sub〉6〈/sub〉 weakens the slow-dynamic state, widens the low-temperature distribution of relaxation times, and lowers activation energies within the Arrhenius-like relaxation regime.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 493〈/p〉 〈p〉Author(s): Baoshan Cui, Hao Wu, Meixia Chang, Jijun Yun, Yalu Zuo, Meizhen Gao, Kang L. Wang, Li Xi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Domain wall (DW) motion via current induced spin-orbit torque (SOT) and/or a magnetic field in ferromagnet/heavy metal heterostructure has attracted abundant interests due to its potential applications in magnetic memories and logic devices. In this work, we study the influence of the depinning energy barrier on DW motion in the creep regime using the polar magneto-optical Kerr microscopy in the Cr layer decorated Pt/Co/Ta structure. We find that although the SOT efficiency shows a significant enhancement in the Pt/Co/Cr/Ta system, but the current-induced DW motion efficiency still shows an attenuation. We confirm that this unexpected result is caused by the enhanced pinning energy barrier, extracted from the relationship between the cumulative depinning probability (〈em〉P〈/em〉〈sub〉d〈/sub〉) and the depinning time (〈em〉t〈/em〉). Moreover, the relationship between 〈em〉P〈/em〉〈sub〉d〈/sub〉 and 〈em〉t〈/em〉 exhibits preferred exponential distribution, indicating that a single energy barrier governs the depinning behavior in our systems. We also reveal that the energy barrier depends on the interface between the ferromagnet and heavy metal. Our study suggests that the current-induced DW motion efficiency is not only determined by the SOT efficiency, but also the depinning energy barrier.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 493〈/p〉 〈p〉Author(s): Ricardo Francisco Alves, Marcio Assolin Correa, Ramon Alves Torquato, Tibério Andrade dos Passos, Felipe Bohn, Rodolfo Bezerra da Silva, Rodinei Medeiros Gomes, Danniel Ferreira de Oliveira〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Heusler alloy composed by NiMnIn was prepared by induction melting in Argon atmosphere. The thermal martensitic and magnetic transitions of the sample were identified by differential scanning calorimetry. The quasi-static magnetic properties were observed by field-colled, zero-field-colled, and isothermal magnetization curves in a wide range of temperature. Moreover, AC susceptibility measurements were employed to analyze the low-frequency magnetization dynamics. The martensitic state of the sample leads to magnetic disturbances of quasi-diamagnetism and exchange bias behavior. The exchange bias field presented a transition from negative values to positive values with the temperature increasing. Therefore, the results open a way for technological applications of the NiMnIn Heusler alloy, with potential perspectives for the development of spintronic devices.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 492〈/p〉 〈p〉Author(s): Krzysztof Tadyszak, Katarzyna Chybczyńska, Paweł Ławniczak, Alina Zalewska, Bogumił Cieniek, Michał Gonet, Marek Murias〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Complex magnetic behavior of pristine, partially reduced graphene oxide aerogel with C/O ratio of 2.35 (EDS) with full analysis of oxygen rich groups attached to the surface is reported. Purity of the system was confirmed by three techniques: elemental analysis, EDS, EPR at 4.2 K none of them detected traces of transition metal ions, especially iron and manganese. Computer tomography reviled the inside foam structure, showing different stacking inside and at the surface, as well as some structural defects. The foams morphology was confirmed by SEM. Electric measurements show linear voltage current relationship and temperature dependences which could be described in the framework of variable range hopping model. Magnetic susceptibility measurements exhibit very weak ferromagnetic behavior modified by antiferromagnetic interactions and paramagnetism. EPR study confirms two component paramagnetism of Curie and Pauli type.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0304885318321899-ga1.jpg" width="424" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 493〈/p〉 〈p〉Author(s): Yuichi Ishida, Kenji Kondo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We investigate the skyrmion Hall effect using the Landau-Lifshitz-Gilbert (LLG) equation and the Thiele equation, respectively. Then, we find that these methods give different values for the ratio of in-plane skyrmion velocity components when the Gilbert damping constant is relatively small. Since the Thiele equation is derived from the LLG equation by assuming that the skyrmion structure does not change and behaves like a rigid body, the above result suggests that this assumption does not hold when the Gilbert damping constant is relatively small. Therefore, we conclude that the Thiele equation can not describe the systems precisely under the relatively small Gilbert damping constant due to the distortion of the skyrmion structure and that it is mandatory to solve the LLG equation numerically in order to investigate the skyrmion Hall effect accurately. This result is very important since the Gilbert damping constants of metal materials are generally very small.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 493〈/p〉 〈p〉Author(s): D. Wang, Yan Zhou〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Spin-orbit torque in magnetic domain walls was studied by solving the Pauli-Schrödinger equation for the itinerant electrons. The Rashba interaction considered is derived from the violation of inversion symmetry at interfaces between ferromagnets and heavy metals. In equilibrium, the Rashba spin-orbit interaction gives rise to a torque corresponding to the Dzyaloshinskii-Moriya interaction. When there is a current flowing, the spin-orbit torque experienced by the itinerant electrons in short domain walls has both field-like and damping-like components. However, when the domain wall width is increased, the damping-like component, which is the counterpart of the non-adiabatic spin transfer torque, decreases rapidly at the domain wall center. In contrast to the non-adiabatic spin transfer torque, the damping-like spin-orbit torque does not approach to zero far away from the domain wall center, even in the adiabatic limit. The scattering of spin-up and spin-down wave functions, which is caused by the Rashba spin-orbit interaction and the spatial variation of magnetization profile in the domain walls, gives rise to the finite damping-like spin-orbit torque.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 492〈/p〉 〈p〉Author(s): Hayato Masumitsu, Soshi Yoshinaga, Yoshifuru Mitsui, Rie Y. Umetsu, Masahiko Hiroi, Yoshiya Uwatoko, Keiichi Koyama〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Substitution effects on weak itinerant electron ferromagnetism in Cr-based ternary alloy CrAlGe were investigated. It was found that substitution of Cr by 3〈em〉d〈/em〉 transition metal with more electrons than Cr enhanced the spontaneous magnetization and Curie temperature. In addition, the itinerancy of CrAlGe was suppressed with the increase of electrons. The ferromagnetism of CrAlGe was related to electron number rather than lattice parameters. The origin of change of itinerancy was suggested to be Coulomb force caused by effective nuclear charge.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 493〈/p〉 〈p〉Author(s): Jun Zhou, Xiangfeng Shu, Yueqin Wang, Jialin Ma, Yin Liu, Ruiwen Shu, Lingbing Kong〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉(1−x)CoFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉/xCoFe composites with x = 0.3, 0.4, 0.5, 0.6 were synthesized by using a hydrothermal method. The face-centered cubic structure CoFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 adheres to the polyhedral CoFe surface due to strong magnetic interaction to form a composite material. The effects of compositions of the CoFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉/CoFe composites on their microwave absorption properties were studied. The sample with a composition of 0.4CoFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉/0.6Co〈sub〉4〈/sub〉Fe〈sub〉6〈/sub〉 showed optimal reflection loss (RL) −58.22 dB at 12.96 GHz, and the matching thickness was 1.45 mm. Meanwhile, it had an effective absorption frequency range of 11.12–15.28 GHz (RL 〈 −10 dB), with a bandwidth of 4.16 GHz, covering the X-band and Ku-band. The enhanced microwave absorption properties of the composites, as compared with the two components, are attributed to the strengthened natural resonance and the increased impedance matching. Most importantly, by adjusting their composition, the CoFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉/CoFe composites can be used as microwave absorbers at C, X or Ku bands. Consequently, these CoFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉/CoFe composites are promising candidates that can be used to design effective microwave absorbers over wide frequency bands.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S030488531932013X-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 12 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials〈/p〉 〈p〉Author(s): M.D. Hossain, M.A. Hossain, M.N.I Khan, S.S. Sikder, M.A. Hakim〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Doping of rare earth (RE) ions can influence the magnetic properties in spinel ferrites, whereas the phase formation plays an important role. Therefore, it is important to choose the RE ions for doping content to get more benefit. In this work, synthesis of Yttrium doped Co-Zn ferrites were carried out by the method of solid state reaction. Co〈sub〉0.25〈/sub〉Zn〈sub〉0.75〈/sub〉Y〈sub〉x〈/sub〉Fe〈sub〉2-x〈/sub〉O〈sub〉4〈/sub〉 (CZYF) is the general formula of the studied ferrites where x = 0.00, 0.02, 0.04, 0.06 and 0.08. The structural properties of CZYF ferrites were studied by X-ray diffraction (XRD) technique and further refined by Rietveld method. XRD and Rietveld refinement approved that all the CZYF samples are cubic spinel structure and the lattice parameters were increased with increasing Y content. The variation of grain growth and surface morphology of CZYF samples were studied from SEM images indicated that the average grain size increased from 1.412 µm to 2.341 µm. Frequency dependent magnetic properties (complex permeability, loss factor) were observed in the range of 100 Hz to 120 MHz at 300 K (room temperature). The initial permeability of CZYF ferrites are found to decrease with the increase in Y content. This decrease nature of permeability is related to the increase of porosity and average grain size. At three different temperatures (80 K, 200 K and 300 K), we measured saturation magnetization, coercivity and remanent magnetization. The mentioned properties make CZYF ferrites applicable for use as a soft ferrite.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 492〈/p〉 〈p〉Author(s): S. Divya, K. Jeyadheepan, J. Hemalatha〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Magnetoelectric (ME) nanocomposite flexible films composed of electroactive poly(vinylidene fluoride-hexafluoropropylene) (P(VDF-HFP)) and ferromagnetic cobalt ferrite (CoFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉) are fabricated. Single-phase nano CoFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 with cubic spinel structure, synthesized by sol-gel auto combustion technique, is reinforced in different weight percentages to fabricate P(VDF-HFP)-CoFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 films through spin coating technique. Effect of CoFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 on structural, morphological, magnetic, ferroelectric, magnetoelectric properties, and giant magnetoresistance (GMR) behavior has been investigated. It is observed that the reinforcement of CoFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 in P(VDF-HFP) matrix has strongly influenced the formation of β-phase conformation and the degree of structural order. The co-existence of ferroelectric and ferromagnetic orderings in the films has been demonstrated by the P-E and M-H plots. The variations in the polarization effects in the presence of a magnetic field provide the evidence for magnetoelectric cross-coupling in P(VDF-HFP)-CoFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉. The films exhibit a GMR effect from 7% to 100%. In order to demonstrate the use of ME induced GMR in magnetic field sensing, P(VDF-HFP)-CoFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 film (10 wt%) is used in a prototype sensor circuit. A good sensing ability and linear response obtained prove that the prepared film can be used as field sensor.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 493〈/p〉 〈p〉Author(s): Ya-nan Zhang, Naisi Zhu, Peng Gao, Yong Zhao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A highly-sensitive magnetic field sensor based on magnetic fluid (MF) infiltrated ring whispering gallery mode (WGM) resonator was proposed and demonstrated in experiment. The resonator was fabricated by attaching a corrosive hollow-core fiber (HCF) to a tapering fiber, which could generate a WGM resonance spectrum. It was firstly demonstrated in theory and experiment that resonance wavelength of the WGM resonator is sensitive to refractive index of medium that infiltrated in the HCF, and the refractive index sensitivity is related to the wall thickness of the HCF. Then, coupling and packaging of the HCF and the tapering fiber were realized by using a simple method, making the sensor robust and portable. When MF was infiltrated in the HCF, since the refractive index of the MF changed with external magnetic field, the WGM resonance valley shifted in wavelength as a function of the magnetic field, which could be used for magnetic field sensing. Experimental results demonstrated that a high sensitivity of 32.4 pm/Gs could be obtained for magnetic field measurement with good linearity. Besides, the proposed sensor behaved simple and robust structure, simple preparation process, low cost, and compact size.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 493〈/p〉 〈p〉Author(s): Mustafa Akyol, Nazan Demiryurek, Onur Iloglu, Kutluhan Utku Tumen, Faruk Karadag, Ahmet Ekicibil〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Y〈sub〉3〈/sub〉Fe〈sub〉5〈/sub〉O〈sub〉12〈/sub〉 shortly named YIG thin film and various form of Au and YIG thin film stacks have been grown on quartz substrate using both spin-coating and sputtering methods. The films are crystallized in cubic phase after heat treatments process that is optimized to avoid cracks on the surface. The thickness of the YIG layer measured by cross-section electron microscope imaging technique are found as about 80 nm for all samples. While the root-mean-square surface roughness of the YIG film is in sub-nanometer scale, it increases up to 2.86 nm by adding Au layer in the film structure. All films exhibit in-plane easy axis and low coercive field at room temperature. But, the saturation magnetization values of films decrease with Au layer. Whereas the optical transmission value is around 80% for YIG samples above 400 nm, it decreases dramatically with Au in the film stacks. The highest absorption coefficient value is found as ~20 × 10〈sup〉4〈/sup〉 cm〈sup〉−1〈/sup〉 in Q/Au/YIG structure. This strong absorption might come from the localized surface plasmon polaritons of Au noble metals in YIG structure because it enhances the electronic transition from crystal field splitting. As a result of these measurements, it is seen that the Au layer reduces the magnetization of the films, while increases the absorption rate significantly. Due to considerably low production cost of YIG in this work, it might open to commonly use of them in the magneto-optical devices.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 493〈/p〉 〈p〉Author(s): Chuangye Yao, Muhammad Ismail, Aize Hao, Santhosh Kumar Thatikonda, Wenhua Huang, Ni Qin, Dinghua Bao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Oxygen vacancies derived resistive and magnetic switching, was demonstrated in facile solution-processed Au-Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 nanocomposite thin films, in terms of optimum Au content. The metal element introduced is a unique way to create the optimum amount of oxygen vacancies in the dielectric films even in the absence of electrochemically active electrodes. Compared with pure Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 based device, the RRAM device with Au additives showed bipolar switching behavior with uniform Set/Reset voltages, enhanced endurance of 〉10〈sup〉3〈/sup〉 cycles, and stable time-dependent resistances up to 10〈sup〉4〈/sup〉 s. The introduction of Au nanoparticles caused the oxygen vacancies based confined filament growth for optimum switching uniformity and stability. Results showed that Ohmic conduction was dominant at LRS and Schottky emission was dominated at HRS of the devices. Temperature dependence and magnetization change of various resistance states revealed that resistive and magnetic switching was due to the formation and rupture of conductive filaments of Au atoms confined oxygen vacancies with the conversion of cation valence states (Co〈sup〉2+〈/sup〉 and Co〈sup〉3+〈/sup〉). The present study suggests that Au-Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 nanocomposite thin films have a potential for future multifunctional electromagnetic integrated device applications.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 493〈/p〉 〈p〉Author(s): Kai Sun, Shuai Feng, Qian Jiang, Xiaofeng Li, Yaping Li, Runhua Fan, Yan An, Jiaqi Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The soft magnetic composites (SMCs) with high saturation magnetic flux density (〈em〉B〈/em〉〈sub〉s〈/sub〉) and low core loss (〈em〉P〈/em〉〈sub〉s〈/sub〉) have great potential in power electronics. In this work, the insulating SiO〈sub〉2〈/sub〉-Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 layer was prepared by a hydro-thermal method to coat on the surface of the carbonyl iron powders (CIPs). Then, the coated CIPs were heterogeneously distributed in the reduced iron powders (RIPs) to fabricate the intergranular insulated SMCs. The scanning electron microscope (SEM) images and elements analysis confirmed that the surface of the CIPs was covered by a thin insulating layer forming a core-shell structure, and the Si-O-Al bond was detected by FTIR spectra. The resulting samples were annealed at 450 °C in N〈sub〉2〈/sub〉 atmosphere to eliminate the residual stress and improve magnetic properties. The annealed.〈/p〉 〈p〉SMCs containing 25 wt% CIPs@SiO〈sub〉2〈/sub〉-Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 have optimum magnetic properties with a low 〈em〉P〈/em〉〈sub〉s〈/sub〉 of 106.9 W/kg and a highly approximate 〈em〉B〈/em〉〈sub〉s〈/sub〉 of 1.28 T (measured at 500 Hz). Compared with the conventional SMCs, the addition of the coated CIPs can suppress the adverse effect of the nonmagnetic coating layer on magnetic properties; meanwhile, the coated CIPs distributed in the RIPs can reduce the 〈em〉P〈/em〉〈sub〉s〈/sub〉. This work provides a promising approach to the development of SMCs with low hysteresis loss and optimum magnetic properties at low frequency.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 493〈/p〉 〈p〉Author(s): Shyamaldas, M. Bououdina, C. Manoharan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Pure cobalt ferrite nanoparticles were synthesised by hydrothermal method. Cubic spinel structure and improved crystallinity was confirmed by X-ray diffraction analysis. Morphology and average particle size within thenanorange were identified by SEM and TEM. EDX confirmed the presence of Fe, Co, and O elements without any impurities. FT-IR analysis confirmed the presence of vibrational bands in the range of 581–590 cm〈sup〉−1〈/sup〉 and 424–468 cm〈sup〉−1〈/sup〉 ascribed to Fe〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉O and Co〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉O bonds, respectively. The presence of five Raman active modes confirmed the cubic spinel-type structure. Optical study revealed the influence of higher annealing temperature on the band gap; it decreases from 2.60 to 1.53 eV. The dielectric constant, dielectric loss and ac-conductivity were found to varywith increasing frequency range. The shifting of cations between tetrahedral (A) to octahedral (B) sites and vice versa was revealed by Mossbauer spectroscopy. The observed sextets proposed that CoFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 nanoparticles are highly crystalline and magnetically ordered. With increasing annealing temperature, both saturation magnetization and remanence increased, while the coercivity was reduced, which is due to the transition from single domain to multidomain on crossing the critical size of ~40 nm. The Cyclic Voltammetry (CV) test of nanoparticles annealed at 800 °C (S3) revealed excellent specific capacitance at low scan rate.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0304885319317615-ga1.jpg" width="299" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 493〈/p〉 〈p〉Author(s): Xiangxia Wei, Yinhua Liu, Dongjie Zhao, Xuewei Mao, Wanyue Jiang, Shuzhi Sam Ge〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Net-shaped hexagonal barium and strontium ferrites with desirable shapes have been successfully fabricated by the extrusion-based three-dimensional (3D) printing. The influence of milling and calcination conditions on magnetic properties of as-printed hexaferrites are systematically investigated by vibrating sample magnetometry (VSM). The typical ferromagnetic hysteresis loops are observed, revealing that the resulting bulk ferrites derived from the preliminary milled powders are prefect hard magnetic materials. In particular, it is clear that the saturation magnetization is very close to the theoretical values after calcinations. Moreover, the coercivity can be effectively enhanced in the range of 4–6 kOe upon thermal treatment, which is a much higher value compared to ferrites prepared by the conventional ceramic processing. More importantly, the maximum energy product can be significantly improved to as high as around 2.5 MGOe for the 3D-printed strontium ferrites. This is attributed not only to fine precursor powders subjected to mechanical milling, but also to the optimized annealing for grain growth with sizes near the critical single domain limit. Overall, the fabrication of bulk ferrites derived from milled powders using the 3D printing is attractive for the large-scale applications, and may also pave the way for some specific applications, for instance, magnetic separation for nanoparticles.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 491〈/p〉 〈p〉Author(s): Aquil Ahmad, S.K. Srivastava, A.K. Das〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The generalized gradient approximation (GGA) scheme in the first-principles calculations is used to study the effect of L2〈sub〉1〈/sub〉 and XA ordering on the phase stability, half-metallicity and magnetism of Co〈sub〉2〈/sub〉FeAl (CFA) Heusler alloy. Various possible hypothetical structures: L2〈sub〉1〈/sub〉-I, L2〈sub〉1〈/sub〉-II, XA-I, and XA-II are prepared under the conventional L2〈sub〉1〈/sub〉 and inverse XA phases by altering the atomic occupancies at their Wyckoff sites. It is found that the XA-II phase of CFA is the most stable phase energetically among all the structures. The electronic structure calculations without U show the presence of half-metallic (HM) ground state only in L2〈sub〉1〈/sub〉-I structure and the other structures are found to be metallic. However, the electronic structures of CFA are significantly modified in the presence of U, although the total magnetic moments per cell remained the same and consistent with the Slater-Pauling (SP) rule. The metallic ground states of CFA in L2〈sub〉1〈/sub〉-II and XA-II structures are converted into the half-metallic ground states in presence of U but remained the same (metallic) in XA-I structure. The results indicate that the electronic structures are not only dependent on the L2〈sub〉1〈/sub〉 and XA ordering of the atoms but also depend on the choice of U values. So experiments may only verify the superiority of GGA + U to GGA.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 493〈/p〉 〈p〉Author(s): I.V. Kozlov, G.N. Elmanov, K.E. Prikhodko, L.V. Kutuzov, B.A. Tarasov, V.V. Mikhalchik, R.D. Svetogorov, V.S. Mashera, E.S. Gorelikov, S.A. Gudoshnikov〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Amorphous Co〈sub〉69〈/sub〉Fe〈sub〉4〈/sub〉Cr〈sub〉4〈/sub〉Si〈sub〉12〈/sub〉B〈sub〉11〈/sub〉 glass-coated microwires after heat treatment in the temperature range of 250–600 °C during 30 min were investigated. Changes of microstructure, phase composition, fracture morphology, and giant magnetoimpedance (GMI) properties were shown. It is confirmed that a significant increase in the GMI effect was possible not only due to the structural relaxation, but also as a result of phase transformations at the temperature close to the onset of crystallization. It is shown that at the very initial stage of the nucleation of Co nanocrystals, a sharp increase in circumferential diagonal GMI component was observed, a further increase in the amount of the crystalline Co phase was accompanied by degradation of this effect. The most significant GMI ratio was obtained for microwires annealed at 430 °C. At 450 °C and above, an irreversible decrease of the GMI ratio took place. It was caused by the formation of Co crystals, decrease in amount and composition change of the amorphous phase during primary and secondary crystallization. At the final stage of the Co crystals segregation the secondary crystallization of the residual amorphous phase occurred with formation of a metastable τ-phase with a Me〈sub〉23〈/sub〉B〈sub〉6〈/sub〉 type structure. Thermal stability of the τ-phase was analyzed.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 492〈/p〉 〈p〉Author(s): S. Pütter〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The thickness-driven spin-reorientation transition of Co/Au(1 1 1) is studied via 〈em〉in situ〈/em〉 Kerr microscopy. On varying the premagnetization conditions in external field of in-plane or normal orientation, the magnetic switching into a final remanent state from an in-plane field is investigated. The quantitative analysis of the Kerr rotation derived from Kerr microscopy images allows the determination of the population of different magnetic phases as a function of thickness. Coexisting magnetic phases with preferred in-plane and out-of-plane magnetization orientation are identified. The overall switching behaviour is explained by thermal activation of magnetic domains. We show that there is a population of orthogonal bistable magnetic domains, which can be remanently switched between out-of-plane and in-plane orientation by the appropriate magnetic field. This quantity is related to the intersection of the population of states for in-plane and out-of-plane magnetization.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 492〈/p〉 〈p〉Author(s): R. Peña-Garcia, Y. Guerra, F.E.P. Santos, L.C. Almeida, E. Padrón-Hernández〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We present a study about the structural and magnetic properties of Ni-doped yttrium iron garnet nanopowders synthesized by sol-gel. The Rietveld refinement of the X-ray diffractograms indicates the replacement of Fe by Ni in the tetrahedral (〈em〉d〈/em〉) and octahedral (〈em〉a〈/em〉) sites of yttrium iron garnet (YIG) structure. The lattice parameter showed variation associated to the effects of Ni inclusion and structural defects, such as, oxygen vacancies. The morphological analysis evidence particles with a cylindrical shape and the Energy Dispersive Spectroscopy results corroborate the presence of Ni. The average porosity suggests that the replacement of Fe by Ni does not substantially change the textural properties of the particles. The Fourier transform infrared and Raman spectroscopies showed the characteristic absorption bands of YIG and confirmed the substitution in the 〈em〉a〈/em〉-sites and 〈em〉d〈/em〉-sites. The saturation magnetization was studied from the hysteresis loops measurements and present variations with the dopant concentration, associated to the replacement of Fe by Ni and to the oxygen vacancies occurrence. Changes in the coercive field for different dopant concentration were associated to the particle size and pinning centers existence.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0304885318328610-ga1.jpg" width="379" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 3 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials〈/p〉 〈p〉Author(s): Michał Kozanecki, Czesław Rudowicz〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Recent developments in high-magnetic field/high-frequency electron magnetic resonance (HMF-EMR) techniques offer improved capabilities for determination of the spin Hamiltonian (SH) parameters, including the fourth-rank zero field splitting (ZFS) parameters (ZFSPs) for spin 〈em〉S̃〈/em〉 = 2 systems. However, the density functional theory (DFT) and ab-initio methods provide predictions of the ZFS energies from which usually only the second-rank ZFSPs are obtained. Here we present an analytical method for determination of the fourth-rank ZFSPs from the ZFS energy levels for 〈em〉S̃〈/em〉 = 2 ions at orthorhombic sites. This enables assessment of their significance and determination of the dominant parameters. Applications of this method for Fe〈sup〉2+〈/sup〉 in [Fe(H〈sub〉2〈/sub〉O)〈sub〉6〈/sub〉](NH〈sub〉4〈/sub〉)〈sub〉2〈/sub〉(SO4)〈sub〉2〈/sub〉, Fe〈sup〉2+〈/sup〉 in forsterite (Fe〈sup〉2+〈/sup〉:Mg〈sub〉2〈/sub〉SiO〈sub〉4〈/sub〉), and Cr〈sup〉2+〈/sup〉 ions in (ND〈sub〉4〈/sub〉)〈sub〉2〈/sub〉Cr(D〈sub〉2〈/sub〉O)〈sub〉6〈/sub〉(SO〈sub〉4〈/sub〉)〈sub〉2〈/sub〉 and Rb〈sub〉2〈/sub〉Cr(D〈sub〉2〈/sub〉O)〈sub〉6〈/sub〉(SO〈sub〉4〈/sub〉)〈sub〉2〈/sub〉 indicate important role the fourth-rank ZFSPs. The analytical formulas derived by us may be applied to other 3d〈sup〉6〈/sup〉 and 3d〈sup〉4〈/sup〉 (〈em〉S̃〈/em〉 = 2) ions at orthorhombic sites in various hosts for better modeling of spectroscopic and magnetic properties of these systems.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 492〈/p〉 〈p〉Author(s): Kingshuk Mallick, Aditya A. Wagh, P.S. Anil Kumar〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We observe an exchange bias at low temperatures in polycrystalline ferrimagnetic MgFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 (MFO) films grown on Si(100), emerging from Antiferromagnetic (AFM)-like interactions at defect sites, concentrated predominantly at the grain boundaries. In this report, we show it is possible to utilize these AFM interactions to get enhanced spin transport utilizing the spin Seebeck effect (SSE). The temperature dependence of the SSE signal in two films with different defect densities allowed us to identify a unique temperature window for both films where an enhanced SSE signal was observed. Such enhancement has been reported in different Ferromagnet (FM)/AFM bilayer systems, but its observation in a single layer hosting both FM-AFM interactions makes our results attractive. Temperature dependent SQUID magnetometry revealed two distinct regions of strong and weak coupling for the FM-AFM interactions. The weak coupling region is characterized by a distribution of AFM energy barriers (〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si7.svg"〉〈mrow〉〈mi mathvariant="normal"〉Δ〈/mi〉〈/mrow〉〈/math〉E), which can modify the spin conductance across the FM-AFM boundary and hence, affect the spin transport. Indeed, we find that the same functional form fits both the 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si8.svg"〉〈mrow〉〈mi mathvariant="normal"〉Δ〈/mi〉〈/mrow〉〈/math〉E distribution and the SSE temperature evolution for both films. This study should aid in the understanding of SSE in the large class of polycrystalline materials with inherent growth induced defect densities and illustrate the significance of magnetically disordered phases in spin transport.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 492〈/p〉 〈p〉Author(s): Takahide Kubota, Zhenchao Wen, Koki Takanashi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A half-metal is an ideal spin source to realize extremely large magnetoresistance effects because of the completely spin-polarized density of states at the Fermi level, and Heusler alloy is a material class for which several compositions are known to exhibit half-metallic properties. Current perpendicular-to-plane (CPP) giant magnetoresistance (GMR) effect is a resistance change that depends upon the relative angle of the magnetization vectors in magnetic layers separated by thin non-magnetic layer(s), which can be utilized for magnetic sensor applications. Over the last decade, the resistance change of CPP-GMR has been found to enhance greatly when using half-metallic Heusler alloys. In this article, the history of Heusler alloy based CPP-GMR is briefly reviewed, including the authors’ recent results on the analysis of the spin asymmetry coefficients based on the Valet-Fert model. Finally, the degradation of half-metallic spin polarization at interfaces is discussed and a future prospect is described.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 3 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials〈/p〉 〈p〉Author(s): M. Ozcan, S. Ozen, M. Yagmurcukardes, H. Sahin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Novel stable ultra-thin phases of europium oxide are investigated by means of state-of-the-art first principles calculations. Total energy calculations show that single layers of EuO〈sub〉2〈/sub〉 and Eu(OH)〈sub〉2〈/sub〉 can be stabilized in an octahedrally coordinated (1T) atomic structure. However, phonon calculations reveal that although both structures are energetically feasible, only the 1T-EuO〈sub〉2〈/sub〉 phase has dynamical stability. The phonon spectrum of 1T-EuO〈sub〉2〈/sub〉 displays three Raman active modes; a non-degenerate out-of-plane 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mrow〉〈msub〉〈mrow〉〈mi mathvariant="normal"〉A〈/mi〉〈/mrow〉〈mrow〉〈mn〉1〈/mn〉〈mi〉g〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 mode at 353.5 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si2.svg"〉〈mrow〉〈msup〉〈mrow〉〈mtext〉cm〈/mtext〉〈/mrow〉〈mrow〉〈mo〉-〈/mo〉〈mn〉1〈/mn〉〈/mrow〉〈/msup〉〈/mrow〉〈/math〉 and two doubly-degenerate in-plane 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si3.svg"〉〈mrow〉〈msub〉〈mrow〉〈mi mathvariant="normal"〉E〈/mi〉〈/mrow〉〈mrow〉〈mi〉g〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 modes at 304.3 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si4.svg"〉〈mrow〉〈msup〉〈mrow〉〈mtext〉cm〈/mtext〉〈/mrow〉〈mrow〉〈mo〉-〈/mo〉〈mn〉1〈/mn〉〈/mrow〉〈/msup〉〈/mrow〉〈/math〉. Furthermore, magnetic ground state and electronic band dispersion calculations show that the single layer EuO〈sub〉2〈/sub〉 is a metal with net magnetic moment of 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si5.svg"〉〈mrow〉〈msub〉〈mrow〉〈mn〉5〈/mn〉〈/mrow〉〈mrow〉〈mi〉μ〈/mi〉〈mi〉B〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 per unitcell resulting in a half-metallic ferrimagnetic behavior. Moreover, robustness of the half-metallic ferrimagnetic characteristics of EuO〈sub〉2〈/sub〉 is confirmed by the application of electric field and charging. Single layer 1T-EuO〈sub〉2〈/sub〉, with its stable ultra-thin structure and half-metallic ferrimagnetic feature, is a promising novel material for nanoscale electronic and spintronic applications.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 European Polymer Journal, Volume 119〈/p〉 〈p〉Author(s): Andrés Felipe Chamorro Rengifo, Natalia Marcéli Stefanes, Jessica Toigo, Cassiana Mendes, Débora Fretes Argenta, Marta Elisa Rosso Dotto, Maria Cláudia Santos da Silva, Ricardo José Nunes, Thiago Caon, Alexandre Luis Parize, Edson Minatti〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Intact carboxymethyl-hexanoyl chitosan/dodecyl sulfate nanoparticles loaded with pyrazoline H3TM04 were dispersed in biodegradable PEO-chitosan nanofiber mats (PEOChNps) for application in skin cancer treatment. The nanomaterial was formed by co-electrospinning in aqueous solution. The structural and morphological properties of the PEOChNps were investigated by FEG-SEM, TEM, AFM, FTIR, DSC and TGA. The PEOChNps nanofibers showed a narrow size distribution (197.8 ± 4.1 nm) with a homogenous distribution of the nanoparticles inside the nanofibers, promoting the controlled release of H3TM04 from both diffusion and erosion processes over a period of 120 h. An increased transport rate of H3TM04 through the epidermis was also found when PEOChNps was used as the carrier. In 〈em〉in vitro〈/em〉 cytotoxicity assays, the incorporation of H3TM04 into the nanocarriers increased its cytotoxic effect toward B16F10 melanoma cells. These findings suggest that the proposed nanofiber mats could be used for controlled drug release in local chemotherapy treatment for skin cancer.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0014305719311279-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 492〈/p〉 〈p〉Author(s): Jianlei Shen, Qingqi Zeng, Hongguo Zhang, Xuekui Xi, Enke Liu, Wenhong Wang, Guangheng Wu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, new all-〈em〉d〈/em〉-metal Heusler alloys Fe〈sub〉50−x〈/sub〉Cr〈sub〉25+x〈/sub〉V〈sub〉25〈/sub〉 (x = 0–25) were investigated on the behaviors of atomic configuration, lattice constant change, and ferromagnetism from the aspects of theoretical calculations and experiments. The theoretical calculations found that both end-member compounds Fe〈sub〉50〈/sub〉Cr〈sub〉25〈/sub〉V〈sub〉25〈/sub〉 (x = 0) and Cr〈sub〉50〈/sub〉Fe〈sub〉25〈/sub〉V〈sub〉25〈/sub〉 (x = 25) prefer to crystallize in Hg〈sub〉2〈/sub〉CuTi-type (space group: 216) structure rather than Cu〈sub〉2〈/sub〉MnAl-type (space group: 225) one. During the whole substitution process, the structure of Fe〈sub〉50−x〈/sub〉Cr〈sub〉25+x〈/sub〉V〈sub〉25〈/sub〉 alloys remains Hg〈sub〉2〈/sub〉CuTi-type structure, taking the path from 216 to 216, but with different degrees of BC-site disorder. Both the experimental and theoretical results reveal that the lattice constant increases first, and then abnormally decreases, showing a maximum at Cr40, due to the enhanced covalent 〈em〉d〈/em〉-〈em〉d〈/em〉 hybridizations between the transition metals. The magnetic moment and Curie temperature tuned by Cr substitution vary remarkably between 3.3 and 1.15 μ〈sub〉B〈/sub〉/f.u. and between 700 and 170 K, respectively, which indicates that the Cr substitution for Fe alters the spin polarizations and exchange interactions in the system. These results provide new insights into the atomic configuration, magnetism and bonding effect in all-〈em〉d〈/em〉-metal Heusler alloys based on the 〈em〉d〈/em〉-〈em〉d〈/em〉 hybridizations.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 European Polymer Journal, Volume 119〈/p〉 〈p〉Author(s): Javier Quílez-Bermejo, Alessio Ghisolfi, Daniel Grau-Marín, Emilio San-Fabián, Emilia Morallón, Diego Cazorla-Amorós〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉P-postmodified polyaniline was obtained by reacting phosphorus trichloride (PCl〈sub〉3〈/sub〉) and chlorodiphenylphosphine (PPh〈sub〉2〈/sub〉Cl) and polyaniline (PANI), under mild conditions. The reaction was found to be very selective, as only the imine groups were involved in the P-functionalization, and efficient as well, affording a P-loading of 3 at.% and 5 at.% for PPh〈sub〉2〈/sub〉Cl and PCl〈sub〉3〈/sub〉, respectively. All the polymers were characterized by different techniques and the results were endorsed by theoretical calculations. Experimental and Density Functional Theory results proved that the reaction occurs through the imine groups and the phosphorus atoms, generating N〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉P bonds. The electrochemical properties of the N〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉P modified materials were evaluated and the catalytic activity towards oxygen reduction reaction was measured. It was found that a high concentration of phenyl groups from PPh〈sub〉2〈/sub〉Cl (about 3 at.%) affected negatively the activity of the catalyst since they prevented the access of the oxygen molecules to the catalytic active sites. However, a lower amount of 〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉PPh〈sub〉2〈/sub〉 groups (1 at.%) or the use of PCl〈sub〉3〈/sub〉 avoided this hindrance and resulted in an improved catalytic activity with respect to pristine PANI.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0014305719309231-ga1.jpg" width="273" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 491〈/p〉 〈p〉Author(s): M. Sarathbavan, Hanuma Kumar Dara, Tripta Parida, K. Ramamurthi, K. Kamala Bharathi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We report on temperature dependent magnetization and anisotropy properties, magnetic interactions at low temperatures, high temperature magnetic properties and frequency dependent dielectric properties of 0.3NiFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉–0.7Na〈sub〉0.5〈/sub〉Bi〈sub〉0.5〈/sub〉TiO〈sub〉3〈/sub〉 nanocomposites. X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) techniques are employed to study the crystal structure, morphology and the chemical state of the NiFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 (NFO) nanoparticles, Na〈sub〉0.5〈/sub〉Bi〈sub〉0.5〈/sub〉TiO〈sub〉3〈/sub〉 (NBTO) nanorods and nanocomposites. XRD and Raman spectroscopy studies indicate the formation of NFO, NBTO and the nanocomposites in pure phase. SEM and TEM images indicates the presence of both nanoparticles (from NFO) and nanorods (from NBTO) in the 0.3NiFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉–0.7Na〈sub〉0.5〈/sub〉Bi〈sub〉0.5〈/sub〉TiO〈sub〉3〈/sub〉 nanocomposites and the lattice planes with respect to both the phases are confirmed from the selected area diffraction pattern. Magnetization measurements at various temperatures (300 K, 40 K, 10 K and 2 K), field cooled (FC) and zero field cooled (ZFC) magnetization from 300 K to 2 K are measured for the nanocomposites. Saturation magnetization value at 300 K and 2 K for the nanocomposites is seen to be 14.62 emu/g and 16.80 emu/g respectively. Existence of spin glass behavior and competing magnetic interactions in the 0.3NiFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉–0.7Na〈sub〉0.5〈/sub〉Bi〈sub〉0.5〈/sub〉TiO〈sub〉3〈/sub〉 nanocomposites is confirmed from the ZFC and FC magnetization studies. Curie temperature value for 0.3NiFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉–0.7Na〈sub〉0.5〈/sub〉Bi〈sub〉0.5〈/sub〉TiO〈sub〉3〈/sub〉 nanocomposites is observed to be 900 K. Frequency dependent dielectric studies shows the relaxation behavior of the nanocomposites with two relaxation times of 5.803 × 10〈sup〉−2〈/sup〉 s and 2.770 × 10〈sup〉−4〈/sup〉 s arising from NFO and NBTO phases.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0304885319321961-ga1.jpg" width="499" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 491〈/p〉 〈p〉Author(s): Archana Kumari, C. Dhanasekhar, A.K. Das〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The structural, magnetic and transport properties of the layered RBaCo〈sub〉2〈/sub〉O〈sub〉5.5±δ〈/sub〉 cobaltites are sensitive to the oxygen stoichiometry. In this present study, we report the presence of a low-temperature magnetic glassy state in electron-doped polycrystalline YBaCo〈sub〉2〈/sub〉O〈sub〉5.5〈/sub〉 cobaltite. The ac magnetization studies show the absence of conventional spin glass features, while the various dc magnetization studies demonstrate the presence of non-equilibrium magnetic glassy state at low temperature. The magnetic glassy state of this sample results from the kinetic arrest of the first order ferro (or ferri) to antiferromagnetic transition. The role of electron doping in the occurrence of magnetic glassy phenomena is discussed in terms of magnetic phase separation involving the Co〈sup〉3+〈/sup〉/Co〈sup〉2+〈/sup〉 clusters of the ferrimagnetic phase in the Co〈sup〉3+〈/sup〉/Co〈sup〉3+〈/sup〉 antiferromagnetic matrix.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 491〈/p〉 〈p〉Author(s): Xu Zheng, Tian Gao, Wei Jing, Xingyu Wang, Yongsheng Liu, Bin Chen, Hongliang Dong, Zhiqiang Chen, Shixun Cao, Chuanbing Cai, Vyacheslav V. Marchenkov〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Magnetic properties of polycrystalline La〈sub〉1-〈/sub〉〈em〉〈sub〉x〈/sub〉〈/em〉Ca〈em〉〈sub〉x〈/sub〉〈/em〉Mn〈sub〉0.9〈/sub〉Cu〈sub〉0.1〈/sub〉O〈sub〉3〈/sub〉 (0.02 ≤ 〈em〉x〈/em〉 ≤ 0.4) have been investigated in detail. All samples show a clear ferromagnetic-paramagnetic transition. The Curie temperature 〈em〉T〈/em〉〈sub〉C〈/sub〉 decreases with increasing Ca-dopant. Inverse susceptibility of all the samples deviates from Curie-Weiss law above 〈em〉T〈/em〉〈sub〉C〈/sub〉, indicating the presence of a short range ferromagnetic and/or antiferromagnetic ordering state in the paramagnetic background. For 0.02 ≤ 〈em〉x〈/em〉 ≤ 0.2, the upward deviation is attributed to antiferromagnetic interactions, while the downward for 〈em〉x〈/em〉 ≥ 0.3 samples is caused by a Griffiths-like behavior, which is suppressed by an applied field. A charge ordering transition associated with an antiferromagnetic phase is detected in 〈em〉x〈/em〉 ≥ 0.3 samples, the melting of which results in a spin reorientation transition and a new FM phase. Finally, the phase diagrams of this manganite system have been established.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 491〈/p〉 〈p〉Author(s): Jae-Hyoung You, Sungjoon Choi, Seung-young Park, Sang-Im Yoo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A partial substitution of Zn〈sup〉2+〈/sup〉 for the Fe〈sup〉2+〈/sup〉 site of BaY-type hexaferrite was found to be effective for the improvement of microwave absorption properties in 0.5–18 GHz. For this study, the composites of polycrystalline Ba〈sub〉2〈/sub〉Fe〈sub〉2-〈/sub〉〈em〉〈sub〉x〈/sub〉〈/em〉Zn〈em〉〈sub〉x〈/sub〉〈/em〉Fe〈sub〉12〈/sub〉O〈sub〉22〈/sub〉 (Ba〈sub〉2〈/sub〉Fe〈sub〉2-〈/sub〉〈em〉〈sub〉x〈/sub〉〈/em〉Zn〈em〉〈sub〉x〈/sub〉〈/em〉Y, 0.5 ≤ 〈em〉x〈/em〉 ≤ 2.0) and epoxy resin were fabricated with various hexaferrite volume fractions (〈em〉V〈/em〉〈sub〉f〈/sub〉) of 30–90%. As a result, Ba〈sub〉2〈/sub〉Zn〈em〉〈sub〉x〈/sub〉〈/em〉Fe〈sub〉2-〈/sub〉〈em〉〈sub〉x〈/sub〉〈/em〉Y (〈em〉x〈/em〉 = 0.5–1.5) composites having the partial substitution of Zn〈sup〉2+〈/sup〉 exhibited larger complex permittivity values than fully Zn〈sup〉2+〈/sup〉 substituted composite of Ba〈sub〉2〈/sub〉Zn〈sub〉2〈/sub〉Y (〈em〉x〈/em〉 = 2.0) due to an electron hopping between Fe〈sup〉2+〈/sup〉 and Fe〈sup〉3+〈/sup〉 ions. Because of the enhanced permittivity, Ba〈sub〉2〈/sub〉Fe〈sub〉2-〈/sub〉〈em〉〈sub〉x〈/sub〉〈/em〉Zn〈em〉〈sub〉x〈/sub〉〈/em〉Y (〈em〉x〈/em〉 = 0.5–1.5) composites with 30% of 〈em〉V〈/em〉〈sub〉f〈/sub〉 possessed better impedance matching characteristics compared with other composites having larger 〈em〉V〈/em〉〈sub〉f〈/sub〉 values. Consequently, Ba〈sub〉2〈/sub〉Fe〈sub〉2-〈/sub〉〈em〉〈sub〉x〈/sub〉〈/em〉Zn〈em〉〈sub〉x〈/sub〉〈/em〉Y (〈em〉x〈/em〉 = 0.5–1.5) composites exhibited excellent RL values lower than −50 dB with the thickness values ranging from 1.52 to 1.80 mm.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 491〈/p〉 〈p〉Author(s): Jia-hao Liu, Xiao-kuo Yang, Huan-qing Cui, Bo Wei, Cheng Li, Yabo Chen, Mingliang Zhang, Chuang Li, Dan-na Dong〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Fast 180° magnetization switching is one of the main challenges for straintronics to be used in magnetic storage and logic. By deflecting the electrodes pair axis by a small angle from the long axis of a uniaxial multiferroic nanomagnet, the voltage pulse can directly induce the nanomagnet to complete repeatable 180° switchings without requiring a start-up time. The dynamic magnetization of the repeatable 180° switching in the nanomagnet and the optimal voltage pulse waveform is simulated through micromagnetic method. Is obtained by simulation calculation, when the electrodes pair axis tilting angle is about 5°, the required stress is small, the switching frequency is high, and the initial switching time is short, which is about 1/5 of the existing research scheme. The switching at room temperature is also calculated by a mathematical model. The switching time is longer under the influence of thermal fluctuations. These findings may provide guidance for the application of straintronic devices.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 20 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials〈/p〉 〈p〉Author(s): Maria M. Markina, Konstantin V. Zakharov, Peter S. Berdonosov, Valery A. Dolgikh, Elena S. Kuznetsova, Sergei A. Klimin, Oleg B. Yumashev, Alexander N. Vasiliev〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The kagome lattice of copper ions in francisite-type compounds is quite sensitive to external stimuli, being easily affected by temperature and magnetic field. The rare-earth ions inserted between buckled layers of transition metal add new dimension to magnetism in these systems. Neodymium francisites, Cu〈sub〉3〈/sub〉Nd(SeO〈sub〉3〈/sub〉)〈sub〉2〈/sub〉O〈sub〉2〈/sub〉X (X = Cl, Br), experience long range magnetic order at 〈em〉T〈/em〉〈sub〉N〈/sub〉 = 34 K (Cl) or 35.2 K (Br) and spin reorientation transition at 〈em〉T〈/em〉〈sub〉R〈/sub〉 = 4 K (Cl) or 4.6 K (Br) marked by sharp anomalies in magnetization 〈em〉M〈/em〉, specific heat 〈em〉C〈/em〉〈sub〉p〈/sub〉, and optical spectra. The spin reorientation of Cu〈sup〉2+〈/sup〉 ions is due to 〈em〉d〈/em〉-〈em〉f〈/em〉 interaction of transition and rare-earth magnetic subsystems. Under action of modest external field 〈em〉B〈/em〉 〈 2 T both compounds exhibit metamagnetic phase transition, largely hysteretic in case of Cl compound at 〈em〉T〈/em〉 〈 〈em〉T〈/em〉〈sub〉R〈/sub〉.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0304885319321328-ga1.jpg" width="285" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 European Polymer Journal, Volume 118〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 15 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 492〈/p〉 〈p〉Author(s): Seyedeh Mansoureh Hashemi, Saeed Hasani, Khadijeh Jahanbani Ardakani, Fatemeh Davar〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, cobalt ferrite (CoFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉) nanoparticles were synthesized by a novel sol-gel auto-combustion in the simultaneous presence of ethylene glycol and agarose as complexing agents, and their effects on the structure, morphology, and magnetic properties of this ferrite were investigated. All synthesized nanoparticles were structurally and morphologically characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and Fourier transform infrared spectroscopy (FT-IR) methods. The results confirmed that the single-phase spinel CoFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 nanoparticles were obtained. Analysis of the XRD patterns was carried out by Rietveld refinement technique to estimate the particle size, lattice parameter, and the cation distribution between the tetrahedral and octahedral sites. The Rietveld refinement data revealed that the simultaneous presence of ethylene glycol and agarose reduced the average size of crystallites. Moreover, FE-SEM micrographs showed that the agglomeration of the nanoparticles was reduced by the addition of these agents. Magnetic characteristics of the synthesized nanoparticles were characterized by a vibrating sample magnetometer (VSM). The results revealed that the saturation magnetization and coercivity could simultaneously be increased by the proper addition of ethylene glycol and agarose, so that these magnetic properties can be used to design magnetic coding and sensing devices.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 493〈/p〉 〈p〉Author(s): Peng Zhao, Gang Chen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Based on density functional theory combined with Keldysh non-equilibrium Green’s function formalism, we investigate the spin-polarized transport properties of planar four-coordinate Fe complexes-based molecular devices with carbon nanotube bridges and electrodes. The results show that these systems can exhibit perfect spin filtering, large giant magnetoresistance and low-bias negative differential resistance effects with the external magnetic field modulation. The underlying mechanism is analyzed by spin-resolved transmission spectra, projected density of states, and spatial distributions of corresponding molecular projected self-consistent Hamiltonian orbitals. On the basis of these intriguing transport properties, we further design basic spin molecular Boolean logic gates, such as YES, NOT, AND, NAND, XOR, NXOR, OR and NOR logic gates.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉Based on the intriguing spin-polarized transport properties of PFCF-based molecular devices with carbon nanotube bridges and electrodes, basic spin molecular Boolean logic gates are designed.〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0304885319324552-ga1.jpg" width="459" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 17 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials〈/p〉 〈p〉Author(s): M.M. van de Loosdrecht, S. Waanders, H.J.G. Krooshoop, B. ten Haken〈/p〉

Description: 〈p〉Publication date: 15 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 492〈/p〉 〈p〉Author(s): Jun He, Dongyong Shan, Shuoqing Yan, Heng Luo, Can Cao, Yuhui Peng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Ti〈sub〉3〈/sub〉C〈sub〉2〈/sub〉 MXene is highly desirable as a potential microwave absorbent due to its positive dielectric loss ability. However, lack of magnetic loss for pure Ti〈sub〉3〈/sub〉C〈sub〉2〈/sub〉 MXene results in unbalanced electromagnetic parameters and poor impedance matching. In this paper, the laminated Ti〈sub〉3〈/sub〉C〈sub〉2〈/sub〉 MXene was synthesized using HF etching process. Then, the magnetic FeCo-decorated Ti〈sub〉3〈/sub〉C〈sub〉2〈/sub〉 MXene (FeCo-Ti〈sub〉3〈/sub〉C〈sub〉2〈/sub〉 MXene) composite was fabricated for the first time via a in-situ hydrothermal method. The incorporation of magnetic FeCo nanoparticles on Ti〈sub〉3〈/sub〉C〈sub〉2〈/sub〉 MXene can enhance microwave absorption property. Specifically, the FeCo-Ti〈sub〉3〈/sub〉C〈sub〉2〈/sub〉 MXene composite displayed a broad effective bandwidth (RL 〈 −10 dB) of 8.8 GHz with only 1.6 mm. This excellent microwave absorbing performance was mainly attributed to strong microwave attenuation ability and improved impedance matching. The results of this work confirm that the FeCo-Ti〈sub〉3〈/sub〉C〈sub〉2〈/sub〉 MXene composite could be favourable as highly competitive microwave absorbent.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 2 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials〈/p〉 〈p〉Author(s): Roland H. Tarkhanyan, Dimitris G. Niarchos〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The influence of the magnetic field on the thermoelectric figure of merit in semiconducting materials is studied theoretically. One of the important issues is the urgency to distinguish the various conditions under which the magneto-thermoelectric effects can be observed. Isothermal effects take place when there is no temperature gradient in the direction perpendicular to the plane containing the magnetic field and applied temperature gradient. Adiabatic effects occur when there is no heat current in the same transverse direction while a temperature gradient arises due to the Righi-Leduc effect. In this paper we examine how the application of an external magnetic field can vary the figure of merit 〈em〉ZT〈/em〉 under isothermal and adiabatic conditions and establish relations among them for both longitudinal and transverse Nernst-Ettingshausen effects. Analytical expressions for the figures of merit are obtained in semiconductors with both non-degenerate and strongly degenerate statistics of charge carriers, in limiting cases of weak and classically strong magnetic fields.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 492〈/p〉 〈p〉Author(s): Deepika Rani, Lakhan Bainsla, K.G. Suresh, Aftab Alam〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this report, structural, electronic, magnetic and transport properties of quaternary Heusler alloys CoRuMnGe and CoRuVZ (Z = Al, Ga) are investigated. All the three alloys are found to crystallize in cubic structure. CoRuMnGe exhibits L2〈sub〉1〈/sub〉 structure whereas, the other two alloys have B2-type disorder. For CoRuMnGe and CoRuVGa, the experimental magnetic moments are in close agreement with the theory as well as those predicted by the Slater-Pauling rule, while for CoRuVAl, a relatively large deviation is seen. The reduction in the moment in case of CoRuVAl possibly arises due to the anti-site disorder between Co and Ru sites as well as V and Al sites. Among these alloys, CoRuMnGe has the highest 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si63.svg"〉〈mrow〉〈msub〉〈mrow〉〈mi mathvariant="normal"〉T〈/mi〉〈/mrow〉〈mrow〉〈mi〉C〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 of 560 K. Resistivity variation with temperature reflects the half-metallic nature in CoRuMnGe alloy. CoRuVAl shows metallic character in both paramagnetic and ferromagnetic states, whereas the temperature dependence of resistivity for CoRuVGa is quite unusual. In the last system, 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si64.svg"〉〈mrow〉〈mi〉ρ〈/mi〉〈/mrow〉〈/math〉 vs. T curve shows an anomaly in the form of a maximum and a region of negative temperature coefficient of resistivity (TCR) in the magnetically ordered state. The 〈em〉ab initio〈/em〉 calculations predict nearly half-metallic ferromagnetic state with high spin polarization of 91, 89 and 93% for CoRuMnGe, CoRuVAl and CoRuVGa respectively. In the case of CoRuMnGe, the XRD analysis reveals that the Co and Ru sites are equally probable. Hence, to investigate the electronic properties of the experimentally observed structure, the Co-Ru swap disordered structures of CoRuMnGe alloy are also simulated and it is found that the disordered structures retain half-metallic nature, high spin polarization with almost same magnetic moment as in the ideal structure. Nearly half-metallic character, high 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si65.svg"〉〈mrow〉〈msub〉〈mrow〉〈mi mathvariant="normal"〉T〈/mi〉〈/mrow〉〈mrow〉〈mi〉C〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 and high spin polarization make CoRuMnGe alloy promising for room temperature spintronic applications.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 492〈/p〉 〈p〉Author(s): Alessandra Manzin, Riccardo Ferrero〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This paper presents a GPU-parallelized 2.5D micromagnetic solver for the efficient calculation of the magnetization configuration and hysteresis loop of 3D random distributions of magnetic thin-film objects, strongly interacting in the space. To well-reproduce complex shapes, the exchange field is calculated with a finite difference approach able to handle non-structured meshes. To enable the treatment of many objects, the magnetostatic field is locally separated into two contributions: an internal and an external one. The first term includes the magnetostatic interactions internal to each object and is obtained by numerically solving the Green’s integral equation. The second term describes the inter-object magnetostatic interactions and it is determined by approximating each object as a collection of magnetic dipoles, associated with mesh elements. The accuracy and computational efficiency of the solver are analysed by comparison to a standard 3D-FFT code and to a reference code, where all the magnetostatic field terms are evaluated by numerically solving the Green’s integral equation.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 492〈/p〉 〈p〉Author(s): Shivani Sharma, Poonam Yadav, Tusita Sau, Premakumar Yanda, Peter J. Baker, Ivan da Silva, A. Sundaresan, N.P. Lalla〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉SrTi〈sub〉0.5〈/sub〉Mn〈sub〉0.5〈/sub〉O〈sub〉3〈/sub〉 (STMO) is a chemically disordered perovskite having random distribution of Ti and Mn over 1〈em〉b〈/em〉 site. Striking discrepancies about the structural and magnetic properties of STMO demand detail analysis which is addressed. To explore the magnetic ground state of STMO, static and dynamic magnetic properties were studied over a broad temperature range (2–300 K). The 〈em〉dc〈/em〉 and 〈em〉ac〈/em〉 magnetization shows a cusp like peak at 〈em〉T〈sub〉f〈/sub〉〈/em〉 ~ 14 K, which exhibits field and frequency dependence. The thermoremanent magnetization is characterized by using stretched exponential function and characteristic time suggests the existence of spin clusters. Also, the other features observed in magnetic memory effect, muon spin resonance/rotation and neutron powder diffraction confirm the existence of cluster spin glass state in STMO, rather than the long-range ordered ground state. Intriguingly, the observed spin-relaxation can be attributed to the dilute magnetism due to non-magnetic doping at Mn-site and competing antiferromagnetic and ferromagnetic interactions resulting from the site disorder.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 491〈/p〉 〈p〉Author(s): M. Pugaczowa-Michalska〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The neutron-scattering measurements and the observation of hyperfine interaction of nuclear moments in Pd〈sub〉2〈/sub〉MnGe alloy have prompted a study of disorder in this compound by the density functional theory methods. Two approaches: the coherent-potential approximation (CPA) and supercell modelling were used to gain microscopic insight into the electronic and magnetic properties of disordered Pd〈sub〉2〈/sub〉MnGe. The influence of disorder between Pd and Mn sublattices in Pd〈sub〉2〈/sub〉MnGe on the magnetic moment of Mn atoms is discussed. The presented CPA studies have shown that the small disorder in Pd〈sub〉2〈/sub〉MnGe (between the Pd-Mn sublattices of the L2〈sub〉1〈/sub〉 structure) does not well describe the experimental evidence of antiparallel alignment of magnetic moment of Mn at positions (A,C) and B positions. However, the appearance of antiparallel moment of Mn at positions A and B was predicted for the Pd〈sub〉2〈/sub〉MnGe in the frames of 128-atoms supercell calculations. The generalized gradient approximation (GGA) has been the main basis for the presented supercell first-principles electronic structure calculations. The magnetic moment of Mn(A,C) is found to be small and negative value of −0.177 µ〈sub〉B〈/sub〉. The values of magnetic moment of Mn(B) are between 3.6 µ〈sub〉B〈/sub〉 and 3.72 µ〈sub〉B〈/sub〉. The results obtained for the supercell calculations are consistent with available experiments in the literature. The results of presented calculations in the supercell approach have shown that the disordered Pd〈sub〉2〈/sub〉MnGe can be predicted as a mixture of several supercells.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0304885319308285-ga1.jpg" width="343" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 491〈/p〉 〈p〉Author(s): Anupam Maity, Subha Samanta, Ramaprasad Maiti, Soumi Chatterjee, Debasish Biswas, Dipankar Chakravorty〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Nanodimensional silica-based spin glasses of compositions xCoO-(100-x)SiO〈sub〉2〈/sub〉 with x having values 20 and 30 were synthesized by sol-gel method within mesoporous silica SBA-15 (Santa Barbara Amorphous-15) having a pore diameter ~5.5 nm. X-ray photoelectron spectroscopy (XPS) analysis showed the presence of both Co〈sup〉2+〈/sup〉 and Co〈sup〉3+〈/sup〉 species within the glasses. This caused electronic conduction in this amorphous system. The nanoglasses exhibited resistivity values at room temperature which were about three orders of magnitude lower than those of the corresponding bulk glasses. The resistivity data for the nanodimensional glasses on analysis confirmed the conduction to arise due to small polaron hopping between the localized states represented by these ions with an activation energy in the range 0.08–0.07 eV. The inter-site separation values extracted from the analysis of the resistivity data were found to lie in the range 6.7–6.6 Å. The values of magnetodielectric (MD) parameter for the different nanocomposites were rather large with the highest value found to be in the range 523–49% for the frequencies 1 kHz and 1 MHz in case of nanocomposite with a glass composition 30CoO-70SiO〈sub〉2〈/sub〉. The dissipation factor for the samples was, however, in the range 0.3–1.6. By using suitable measuring frequency the dissipation factor could be brought down to a value less than 1.0 with the M.D. parameter exhibiting values in the range 10–49%. The results were fitted to Catalan’s model based on two dielectrics with different resistivity values connected in series. The satisfactory fit of the experimental data to the theoretical model based on a negative magnetoresistance of the nanoglasses leads to the conclusion that an enhancement of spin polarized electron hopping is the reason behind this effect. The results obtained should be further explored to find applications of these materials as magnetic sensors as well as magnetically controlled supercapacitors.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 491〈/p〉 〈p〉Author(s): Doan Quoc Khoa, Bui Dinh Hoi, Tran Cong Phong〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this paper, we theoretically address the transverse Zeeman magnetic field effects on the frequency-dependent dynamical dielectric function of phosphorene including the refractive index and the absorption coefficient. An effective Hamiltonian model beyond the continuum approximation is employed to obtain the electronic dispersion energy. The linear response theory is applied to calculate the dynamical dielectric function at a certain temperature along both armchair and zigzag edges. Our numerical calculations show that, independent of the direction, the refraction (absorption) intensity decreases (increases) with the optical frequency at all magnetic field strengths. Moreover, we find out that the refraction and absorption processes along the armchair edge do not change after a critical magnetic field and this critical point increases with the optical frequency stemming from the spin-splitting effects. As for the zigzag edge, however, there is a little to no change for these processes with the magnetic field. Further, we observe that, on the average, the dominant contribution to the total magnetic field-dependent dynamical dielectric function comes from the armchair edge originating from the smaller (larger) carrier effective mass (velocity) than the zigzag edge. Tuning the optical responses of phosphorene with the transverse Zeeman magnetic field is useful for practical spintronic applications.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 491〈/p〉 〈p〉Author(s): M.Kh. Hamad, Y. Maswadeh, Kh.A. Ziq〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We investigate the effect of Ni-substitution on the crystalline structure and the critical behavior of Nd〈sub〉0.6〈/sub〉Sr〈sub〉0.4〈/sub〉Mn〈sub〉1−x〈/sub〉Ni〈sub〉x〈/sub〉O〈sub〉3〈/sub〉 〈em〉(0.00〈/em〉 ≤ 〈em〉x〈/em〉 ≤ 〈em〉0.20)〈/em〉 perovskite. X-ray diffraction patterns revealed that the major phase in all samples is the orthorhombic structure with space group 〈em〉Pnma〈/em〉. Rietveld refinement revealed a linear reduction in the lattice parameters along with monotonic reduction in the 〈em〉O2-Mn-O2〈/em〉 angel with increasing Ni concentration. The modified Arrott plots and the Kouvel-Fisher method have been used to analyze the magnetization isotherms near the paramagnetic to ferromagnetic (PM-FM) phase transition. The obtained critical exponents (β, γ and δ) revealed that the 〈em〉Ni〈/em〉-free sample is consistent with 3D-Heisenberg like behavior. However, upon Ni-substitution, the critical exponents exhibit a mean field like behavior. The reliability of the obtained critical exponent (β, γ, and δ) values have been confirmed by the universal scaling behavior of the isothermal magnetization near the transition temperature.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 European Polymer Journal, Volume 119〈/p〉 〈p〉Author(s): Arpit Shukla, Krina Mehta, Jignesh Parmar, Jaimin Pandya, Meenu Saraf〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Microorganisms can utilize an extensive assortment of carbon and nitrogen sources as well as various added nutrients ranging from simple to complex. Depending on the microbe and the metabolic pathway they undergo, these nutrients are efficiently converted into complex and diverse biopolymers with varied physico-chemical properties. Exopolysaccharides (EPS) are biopolymers that primarily contain- carbohydrates. The extensively studied EPS producing bacteria include 〈em〉Leuconostoc mesenteroides〈/em〉, 〈em〉Xanthomonas campestris〈/em〉, 〈em〉Acinetobacter calcoaceticus, Lactobacillus sp〈/em〉. and 〈em〉Alkaligenes〈/em〉 sp. However, some prominent fungal exopolysaccharides produced by 〈em〉Aspergillus niger〈/em〉, 〈em〉Lentinula edodes〈/em〉, 〈em〉Fusarium solani〈/em〉, 〈em〉Botryosphaeria rhodina〈/em〉, 〈em〉Coriolus versicolor〈/em〉 have also been put to commercial use. While the microbes may vary substantially in their physiology, the production of EPS depends largely on the optimization of the growth by varying various parameters influencing growth and the meticulous designing of its production media. EPS acts as an invaluable asset for the producing microbe by providing manifold benefits including but not restricted to: protection against- desiccation, starvation, phagocytosis, UV radiation, environmental stress and water retention. Being eco-friendly and biodegradable, major microbial EPS such as; dextran, xanthan, alginate, hyaluronan, pullulan, chitosan and lentinam have found numerous vital applications in pharmaceutical, agriculture, food and cosmetics industries. This review provides an inclusive insight into the world of microbial exopolysaccharides covering its major aspects, namely- its types, biosynthesis and the factors that influence its production along with various techniques used for its recovery and further characterization. Special emphasis is placed on the applications of EPS in various large-scale commercial and industrial sectors.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0014305719307815-ga1.jpg" width="291" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 20 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials〈/p〉 〈p〉Author(s): N.V. Ter-Oganessian, S.A. Guda, V.P. Sakhnenko, V. Ohanyan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Fluorides in general are characterized by big variety of crystal structures, whereas those containing transition metals also often show sizable magnetic properties. The tendency of fluorine to form linear chain structures in many cases results in low-dimensional magnetism. Despite the plethora of magnetic phenomena in fluorides, their magnetoelectric properties are less studied than those of oxides. In the present work we theoretically study the magnetic and magnetoelectric properties of spin-chain compounds CaFeF〈sub〉5〈/sub〉 and SrFeF〈sub〉5〈/sub〉. The density functional theory is employed for determination of magnetic exchange constants, which are then used in Monte Carlo calculations. The symmetry analysis reveals that CaFeF〈sub〉5〈/sub〉 does not show magnetoelectric properties, whereas SrFeF〈sub〉5〈/sub〉 is a multiferroic.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 492〈/p〉 〈p〉Author(s): Premkumar Murugaiyan, Amitava Mitra, Arun Kumar Patro, Rajat K. Roy, M. Churyukanova, S. Kaloshkin, E. Shuvaeva, Ashis K. Panda〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The influence of P on amorphizing ability, as-quenched microstructure, thermo-physical and soft magnetic properties of Fe–rich (i) Fe〈sub〉81〈/sub〉B〈sub〉15-x〈/sub〉P〈sub〉x〈/sub〉Si〈sub〉2〈/sub〉Nb〈sub〉1〈/sub〉Cu〈sub〉1〈/sub〉 (ii) Fe〈sub〉82〈/sub〉B〈sub〉14-x〈/sub〉P〈sub〉x〈/sub〉Si〈sub〉2〈/sub〉Nb〈sub〉1〈/sub〉Cu〈sub〉1〈/sub〉 and (iii) Fe〈sub〉83〈/sub〉B〈sub〉13-x〈/sub〉P〈sub〉x〈/sub〉Si〈sub〉2〈/sub〉Nb〈sub〉1〈/sub〉Cu〈sub〉1〈/sub〉 (x = 0, 2, 4, 6, 8 at%) melt-spun alloys are investigated. The substitution of P improves amorphization of alloys and restricts the formation of hetero-amorphous microstructure for Fe 83 at% ribbons at around (x = 8). The improvement in short range ordering of P containing clusters with varying Fe content has been discussed within the framework of Cluster-Glue atom model and supported by experimental thermal parameters. The optimal P content in Fe-rich alloys in the range of 4 ≤ x ≤ 6 delivered favourable thermal properties of high primary and secondary crystallization onset temperature viz; T〈sub〉x1〈/sub〉, T〈sub〉x2〈/sub〉 and temperature span ΔT between these onsets. The P substitution drastically restricts the precipitation of secondary crystallites with reduced enthalpy of secondary crystallisation (ΔH〈sub〉2〈/sub〉) during annealing and favourably assists in attaining maximum magnetic moment during the primary crystallization stage. Moreover, the P substitution (4–8 at%) effects refinement of α-Fe nanocrystallites and promotes low coercivity (H〈sub〉c〈/sub〉 〈 20 A/m) in nanocomposite alloys. On contrary, the P substitution linearly reduces saturation magnetization (M〈sub〉s〈/sub〉) by weakening ferromagnetic exchange coupling and ferromagnetic dilution. An optimal content of 4 at% P offers favourable combination of low H〈sub〉c〈/sub〉 and High M〈sub〉s〈/sub〉 in both amorphous and nanocomposite state.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 493〈/p〉 〈p〉Author(s): Jia Liu, Gui Yun Tian, Bin Gao, Kun Zeng, Yang Zheng, Jinzhong Chen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉One challenge of stress measurement by using Magnetic Barkhausen noise (MBN) is to build correlation model between MBN and micro magnetic characterization of the material. In particular, it highly requires a quantitative evaluation for micro-macro magnetic properties characterizing under the stress impaction. In this study, a correlation model between domain wall (DW) motion and MBN under tensile stress is established and promoted. Optical flow (OF) traces motion of magnetic domain images, which can quantify the status of DW motion during magnetization process. When applied field is in stress direction, tensile stress aligns the magnetic domains parallel to the stress direction and makes coercive field decrease. This can make a phenomenon vary of DW motion as well as MBN signal. The average velocity of DW motion (OF value) is proportional to MBN signal under tensile stress. Root mean square (RMS) and mean value are extracted from both DW motion velocity (OF value) and MBN signal to quantitatively analyze the changes under tensile stress to quantify the correlation between micro and macro magnetic parameters. In addition, the correlation model between DW motion and MBN is quantitatively analyzed in different locations to evaluate the repeatability of the correlation, as well as the effect of microstructure on MBN and DW motion under the tensile stress. The correlation coefficient of RMS and mean value show the highly correlation between DW motion and MBN, which in turn sheds deep understanding the micro-macro property-physic mechanisms. The proposed work has potential for interpretation of the statistical properties of MBN under different tensile stress by studying DW motion, which can be further applied for enhancing accuracy on stress measurement.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 European Polymer Journal, Volume 119〈/p〉 〈p〉Author(s): Suzhen Liu, Li Zhang, Xiaohong Chen, Tingting Chu, Yanzhu Guo, Meihong Niu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A novel kind of cationic cellulose-〈em〉g〈/em〉-oligo(ε-caprolactone) amphiphilic polymer (QC-〈em〉g〈/em〉-OCL) was obtained by homogeneous ring-opening polymerization of ε-caprolactone (ε-CL) from quaternized cellulose (QC) in 1-butyl-3-methylimidazolium chloride (BmimCl) ionic liquids. Chemical structures and properties of the copolymers were characterized by FT-IR, 〈sup〉1〈/sup〉H NMR, 〈sup〉13〈/sup〉C NMR, XRD and TGA techniques. The grafting ratios of OCL chain onto QC-〈em〉g〈/em〉-OCL were adjusted by changing the molar ratio of CL to QC. The micelles self-assembled from QC-〈em〉g〈/em〉-OCL were prepared by ultrasonic-assisted dissolution method, and comprehensively analyzed by dynamic light scattering (DLS), TEM and fluorescence spectroscopy techniques. The micelles were in spherical shape with average hydrodynamic radiuses (R〈sub〉h〈/sub〉) in the range of 170–237 nm. Moreover, their critical micelle concentration (CMC) values were decreased from 0.302 mg/mL to 0.089 mg/mL with increasing the degree substitution values of OCL (DS〈sub〉OCL〈/sub〉) from 0.16 to 0.60. The ζ-potentials of micelles in water were ranged from 37.2 mV to 48.3 mV, indicating that the shells of micelles were constituted by ationic quaternary ammonium group. All of these findings established that the cationic cellulose-based micelles would be a promising aqueous carrier for hydrophobic drug.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0014305719312662-ga1.jpg" width="343" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 European Polymer Journal, Volume 118〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 15 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 492〈/p〉 〈p〉Author(s): Atasi Chakraborty, Indra Dasgupta〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We have carried out a detailed first principles electronic structure calculations for d〈sup〉4〈/sup〉 double perovskite iridates Ba〈sub〉2〈/sub〉ScIrO〈sub〉6〈/sub〉 and Sr〈sub〉2〈/sub〉ScIrO〈sub〉6〈/sub〉. Our calculations reveal that the ground state of both the systems to be magnetic contrary to the expectation of 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si14.svg"〉〈mrow〉〈msub〉〈mrow〉〈mi〉J〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="normal"〉eff〈/mi〉〈/mrow〉〈/msub〉〈mo linebreak="goodbreak" linebreakstyle="after"〉=〈/mo〉〈mn〉0〈/mn〉〈/mrow〉〈/math〉 nonmagnetic state induced by strong spin-orbit coupling. Our exact diagonalization calculation with two site many body Hamiltonian suggests that hopping induced delocalization of holes leads to the formation of local moments in these systems.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 493〈/p〉 〈p〉Author(s): Arnab Roy, P.S. Anil Kumar〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉It is well known from theoretical models that a ferromagnetic system should undergo a disorder induced phase transition in its magnetization reversal mode at a critical disorder level 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si18.svg"〉〈mrow〉〈msub〉〈mrow〉〈mi〉R〈/mi〉〈/mrow〉〈mrow〉〈mi〉C〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉, below which, the reversal is characterized by the appearance of the so-called 〈em〉spanning avalanche〈/em〉. The 〈em〉critical〈/em〉 regime above 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si19.svg"〉〈mrow〉〈msub〉〈mrow〉〈mi〉R〈/mi〉〈/mrow〉〈mrow〉〈mi〉C〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 is characterized by power-law distributed avalanche sizes and durations, whose exponents determine the universality class to which the magnetic system belongs. The most commonly studied among these is the size-exponent 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si20.svg"〉〈mrow〉〈mi〉τ〈/mi〉〈/mrow〉〈/math〉, which most theoretical models estimate to be in the range 1.3–1.5. However, experimental determinations of this exponent fall in a much wider interval, between 0.98 and 1.8, well outside the domain of the models. This discrepancy, which is far more common for 2D systems, has not been effectively addressed for more than a decade. In this article, we have determined experimentally the size-exponent ‘〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si21.svg"〉〈mrow〉〈mi〉τ〈/mi〉〈/mrow〉〈/math〉’ in 2D Permalloy(〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si22.svg"〉〈mrow〉〈msub〉〈mrow〉〈mtext〉Ni〈/mtext〉〈/mrow〉〈mrow〉〈mn〉80〈/mn〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si23.svg"〉〈mrow〉〈msub〉〈mrow〉〈mtext〉Fe〈/mtext〉〈/mrow〉〈mrow〉〈mn〉20〈/mn〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉) thin films by measuring Barkhausen noise through the disorder-induced transition using planar Hall effect. This was compared with our simulations of the random field Ising model, an established nucleation model, with a modification that better represented the experimental condition. Our findings indicated that 〈em〉large〈/em〉 ‘〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si24.svg"〉〈mrow〉〈mi〉τ〈/mi〉〈/mrow〉〈/math〉’-values would arise in samples with very low disorder levels well outside the critical regime, where the statistics were non-universal. In such samples, our measured ‘〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si25.svg"〉〈mrow〉〈mi〉τ〈/mi〉〈/mrow〉〈/math〉’ increased monotonically with temperature, which indicated a decrease in the effective disorder with temperature according to the nucleation models. This temperature dependence could be understood in the light of an 〈em〉extended〈/em〉 Néel-Brown model which we had studied earlier, that had predicted a decrease in the width of switching field distribution with increasing temperature. In this context, we also used micromagnetic simulations, which helped to understand the dependence of coercivity on disorder, a property not predicted correctly by the Ising model.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 12 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials〈/p〉 〈p〉Author(s): L. Capogna, V. Granata, B. Ouladdiaf, J.A. Rodriguez-Velamazan, R. Fittipaldi, A. Vecchione〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We have investigated the metamagnetic-like transition in the triple layer ruthenate Sr〈sub〉4〈/sub〉Ru〈sub〉3〈/sub〉O〈sub〉10〈/sub〉 by means of neutron diffraction from single crystals. The magnetic structure of the compound appears to be determined in a complex way by the two substructures of inequivalent ruthenium ions. At T〈sub〉c〈/sub〉=105K the system has a sharp transition into a ferromagnetic state along the 〈em〉c〈/em〉-axis which is driven by the ruthenium atoms in the central octahedra of the triple layers whereas the substructure of the outer ruthenium atoms tend to align in the 〈em〉ab〈/em〉 plane achieving an antiferromagnetic order at the metamagnetic transition T*∼50K. Below T* the strong anisotropy along 〈em〉c〈/em〉 prevails, the outer ruthenium tend to align along the 〈em〉c〈/em〉-axis and the in-plane antiferromagnetic order disappears. This finding confirms the delicate balance between antiferro and ferromagnetic couplings in the (Sr,Ca)〈em〉〈sub〉n〈/sub〉〈/em〉〈sub〉+1〈/sub〉Ru〈em〉〈sub〉n〈/sub〉〈/em〉O〈sub〉3〈/sub〉〈em〉〈sub〉n〈/sub〉〈/em〉〈sub〉+1〈/sub〉 family of compounds, and proves the layer dependence of the magnetic anisotropy in Sr〈sub〉4〈/sub〉Ru〈sub〉3〈/sub〉O〈sub〉10〈/sub〉.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 493〈/p〉 〈p〉Author(s): K.F. Ulbrich, C.E.M. Campos〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Nanocrystalline Nickel sulfide, Ni〈sub〉3〈/sub〉S〈sub〉2〈/sub〉, was prepared mechanochemically using ball milling in an inert atmosphere at room temperature, starting from Ni〈sub〉60〈/sub〉S〈sub〉40〈/sub〉 powder mixtures. X-ray powder diffraction (XRPD) was used to investigate the structural and microstructural evolution of the Ni〈sub〉60〈/sub〉S〈sub〉40〈/sub〉 alloy with milling time. The formation of the trigonal Ni〈sub〉3〈/sub〉S〈sub〉2〈/sub〉 phase (space group R32H) occurs with only 1.5 h, remaining stable up to 24 h of milling. The cell volume, lattice parameters, atomic coordinates, and isotropic atomic dislocation (thermal) parameters of the Ni〈sub〉3〈/sub〉S〈sub〉2〈/sub〉 phase, together with the average crystallite size and micro-strain, were determined from Rietveld analysis of the XRPD data. The average crystallite size decreases from about 37 nm to 22 nm with milling time increasing, with the same behavior happening for micro-strain. The high-temperature experiments showed that the melting point of the nanocrystalline Ni〈sub〉3〈/sub〉S〈sub〉2〈/sub〉 is about 660 °C, which is much lower than bulk. Transmission electron microscopy (TEM) images and electron diffraction patterns confirmed the nanometric size of the crystalline domains but revealed that it belongs to larger agglomerated particles (~100 nm). The nanocrystalline samples have their magnetic properties characterized by vibrating sample magnetometer (VSM), showing an evolution from ferromagnetism to a mixed magnetic state as milling time increases. The high-pressure experiments revealed no phase transitions up to 20 GPa and a bulk modulus of about 143 GPa for the Ni〈sub〉3〈/sub〉S〈sub〉2〈/sub〉 nanophase using the least-squares fit of first-order Murnaghan equation of states.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0304885319315240-ga1.jpg" width="268" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 8 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials〈/p〉 〈p〉Author(s): S. Couture, X. Wang, A. Goncharov, V. Lomakin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A coupled micromagnetic-Maxwell equations solver is presented which takes into account the effect of eddy currents. The proposed solver relies on a strategy involving two parallel solvers, one for the micromagnetic equation, the other for the Maxwell equations, which allows o take advantage of the linearity of the Maxwell equations. Both the micromagnetic and Maxwell equations portions of the solver use a finite element formulation and they perform time integration in parallel with each other using a variable time stepping scheme. A finite element formulation for the Maxwell equations coupled with a micromagnetic solver is proposed. The resulting sparse linear system is solved using a preconditioned iterative method. Since the system matrix changes depending on the time step used, the preconditioner used is an ILU factorization which is interpolated from a set of pre-computed ILU factorizations, thus avoiding the need to recompute a factorization at every time step. The proposed solver is validated by solving a test problem with a known analytical solution. The performance of the solver is illustrated by solving a realistic hard-disk drive recording head model.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 European Polymer Journal, Volume 119〈/p〉 〈p〉Author(s): Isao Yamaguchi, Gintaro Nagase, Aohan Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The reaction of 〈em〉N〈/em〉-(2,4-dinitrophenyl)pyridinium chloride (〈strong〉salt(Cl〈sup〉−〈/sup〉)〈/strong〉) with lithium bis(trifluoromethanesulfonyl)imide (TFSI〈sup〉−〈/sup〉LI〈sup〉+〈/sup〉) and lithium bis(nonafluorobutanesulfonyl)imide (NFSI〈sup〉−〈/sup〉LI〈sup〉+〈/sup〉) resulted in the anion exchange between Cl〈sup〉−〈/sup〉 and TFSI〈sup〉−〈/sup〉 and Cl〈sup〉−〈/sup〉 and NFSI〈sup〉−〈/sup〉 that yielded new Zincke salts, namely 〈strong〉salt(TFSI〈sup〉−〈/sup〉)〈/strong〉 and 〈strong〉salt(NFSI〈sup〉−〈/sup〉)〈/strong〉, respectively. The reaction of 〈strong〉salt(TFSI〈sup〉−〈/sup〉)〈/strong〉 with piperazine, (〈em〉R〈/em〉)-(–)- or (〈em〉S〈/em〉)-(+)-2-methylpiperazines in methanol without the use of a catalyst resulted in the opening of pyridinium ring to yield ionic polymers with 5-piperazinium-2,4-dienylideneammonium bis(trifluoromethanesulfonyl)imide or 5-(2-methylpiperazinium)-2,4-dienylideneammonium bis(trifluoromethanesulfonyl)imide units, namely 〈strong〉polymer(H;TFSI〈sup〉−〈/sup〉)〈/strong〉, 〈strong〉polymer(〈em〉R〈/em〉-Me;TFSI〈sup〉−〈/sup〉)〈/strong〉, and 〈strong〉polymer(〈em〉S〈/em〉-Me;TFSI〈sup〉−〈/sup〉)〈/strong〉, respectively. The reaction of 〈strong〉salt(NFSI〈sup〉−〈/sup〉)〈/strong〉 with piperazine yielded 〈strong〉polymer(H;NFSI〈sup〉−〈/sup〉)〈/strong〉 having a 5-piperazinium-2,4-dienylideneammonium bis(trifluoromethanesulfonyl)imide unit. Model compounds with TFSI〈sup〉−〈/sup〉 or NFSI〈sup〉−〈/sup〉 were synthesized to compare their structures and chemical propeties with those of the corresponding polymers. UV–vis measurements revealed that the π-conjugation system expanded along the polymer chain due to the orbital interaction between the electrons on the two nitrogen atoms of the piperazinium or 2-methylpiperazinium rings. Cyclic voltammetry analysis suggested that the polymers obtained in this study received electrochemical oxidation and reduction.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0014305719307177-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 European Polymer Journal, Volume 119〈/p〉 〈p〉Author(s): Kenji Kanazawa, Sei Uemura〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Herein, electrochromic terpyridine-triphenylamine (Terpy-TPA) polymer films were prepared by electropolymerization of a Terpy-TPA monomer solution in acetonitrile:toluene (1:4, v/v) and. characterized by cyclic voltammogram and absorption spectra in a 50 mM aqueous tetramethylammonium perchlorate as an electrolyte using a standard three-electrode system. The above films could be reversibly color changes between orange (neutral state) and cyan (oxidized state) and maintained a high coloration efficiency of 229 cm〈sup〉2〈/sup〉 C〈sup〉−1〈/sup〉 at 750 nm in the aqueous electrolyte solution.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0014305719312753-ga1.jpg" width="442" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 492〈/p〉 〈p〉Author(s): Wei Zhang, Zhaojun Mo, Wenhao Jiang, Zhihong Hao, Jiawei Luo, Ruijiang Cheng, Guodong Liu, Lan Li, Jun Shen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The EuTi〈sub〉1−x〈/sub〉Al〈sub〉x〈/sub〉O〈sub〉3〈/sub〉 (〈em〉x〈/em〉 = 0.05, 0.1 and 0.15) compounds exhibit the ferromagnetic state. A giant reversible MCE of EuTi〈sub〉1−x〈/sub〉Al〈sub〉x〈/sub〉O〈sub〉3〈/sub〉 (〈em〉x〈/em〉 = 0.05, 0.1, 0.15) compounds was observed, which was attributed to the increase of ferromagnetic ordering. With increasing the Al content, the value of −Δ〈em〉S〈sub〉M〈/sub〉〈sup〉max〈/sup〉〈/em〉 is increased from 11.6 J/kg K to15.6 J/kg K for EuTi〈sub〉1−x〈/sub〉Al〈sub〉x〈/sub〉O〈sub〉3〈/sub〉, and the RC values are 48.4 J/kg for EuTi〈sub〉0.95〈/sub〉Al〈sub〉0.05〈/sub〉O〈sub〉3〈/sub〉, 53.1 J/kg for EuTi〈sub〉0.9〈/sub〉Al〈sub〉0.1〈/sub〉O〈sub〉3〈/sub〉 and 58.2 J/kg for EuTi〈sub〉0.85〈/sub〉Al〈sub〉0.15〈/sub〉O〈sub〉3〈/sub〉 with magnetic field change 0–1 T. Additionally, the maximum value of Δ〈em〉T〈sub〉ad〈/sub〉〈/em〉 is 4.7 K for EuTi〈sub〉0.85〈/sub〉Al〈sub〉0.15〈/sub〉O〈sub〉3〈/sub〉 compound as magnetic field changes 1 T. The EuTi〈sub〉1−x〈/sub〉Al〈sub〉x〈/sub〉O〈sub〉3〈/sub〉 with giant −Δ〈em〉S〈sub〉M〈/sub〉〈/em〉, large RC and large ΔT〈em〉〈sub〉ad〈/sub〉〈/em〉 suggest an important material for magnetic refrigerant at low-temperature.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 492〈/p〉 〈p〉Author(s): Yudeuk Kim, David Juseong Bang, Yonghwan Kim, Jinyong Jung, Namjung Hur, Chun-Yeol You, Kyong Hon Kim〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We have measured the magneto-optic (MO) properties of film-type bismuth substituted yttrium iron garnets (Bi1.5:YIG, Bi〈sub〉1.5〈/sub〉Y〈sub〉1.5〈/sub〉Fe〈sub〉5〈/sub〉O〈sub〉12〈/sub〉) prepared by using metal-organic-decomposition (MOD) method on glass substrates at the 1310-nm and 1550-nm wavelengths. The Verdet constant of the Bi1.5:YIG film in the unsaturated linear magnetization region has been experimentally determined from a sensitive measurement of the Faraday rotation of the Bi1.5:YIG films with a lock-in amplifier and an auto-balanced photoreceiver under alternating magnetic fields. The Bi:YIG films have been deposited on silica glass substrates without any buffer layer and with one of buffer layers of Bi〈sub〉1〈/sub〉Y〈sub〉2〈/sub〉Fe〈sub〉5〈/sub〉O〈sub〉12〈/sub〉 (Bi1:YIG) and Bi〈sub〉1〈/sub〉Fe〈sub〉4〈/sub〉Ga〈sub〉1〈/sub〉Nd〈sub〉2〈/sub〉O〈sub〉12〈/sub〉 (Bi1:NIGG) which are used to compensate mismatch of the lattice constant and thermal expansion coefficient between the film and substrate. The maximum value of the measured Faraday rotation of the Bi1.5:YIG film was over 94.6 and 156.5 °/cm for an applied unsaturated magnetic field of 100 Gauss at wavelengths of 1310 and 1550 nm, respectively, when it was prepared at annealing temperature of 700 °C and annealing speed of 1 °C/min. The absorption coefficients of the Bi1.5:YIG films were measured to be 70 cm〈sup〉−1〈/sup〉 and 330 cm〈sup〉−1〈/sup〉, respectively, at each of the wavelengths, and the average Gilbert damping coefficient of the Bi1.5:YIG film with a Bi1:NIGG buffer layer was measured to be 6.42 ± 18.09 × 10〈sup〉−4〈/sup〉 (with the minimum value of 0 and the maximum value of 24.51 × 10〈sup〉−4〈/sup〉) from a conventional ferromagnetic resonance (FMR) measurement system. Our experimental result indicates that the magneto-optic property of the Bi:YIG films prepared by the MOD method is unstable and fluctuates from run to run although its average magnetic property may be useful for application to compact integrated optical isolators under an easy solution-based fabrication process.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 492〈/p〉 〈p〉Author(s): R.L. Souza, J.C.B. Monteiro, A.O. dos Santos, L.P. Cardoso, L.M. da Silva〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Here, we report the results of structural, magnetic, thermal and magnetocaloric properties of ErCoSn compound. The compound undergoes an antiferromagnetic (AFM) ordering around T〈sub〉N〈/sub〉 = 4.6 K and magnetic correlation is observed above T〈sub〉N,〈/sub〉 up to T = 11 K. Below T〈sub〉N〈/sub〉, a spin-glass state was observed for ErCoSn due to an apparent coexistence of ferromagnetic (FM) interaction with long-range AFM order. External applied magnetic field induces a first-order-like metamagnetic phase transition from AFM to FM state that is responsible for the large values of the maximum isothermal entropy change (−〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si3.svg"〉〈mrow〉〈msubsup〉〈mi mathvariant="normal"〉Δ〈/mi〉〈mrow〉〈mi〉M〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="italic"〉max〈/mi〉〈/mrow〉〈/msubsup〉〈/mrow〉〈/math〉 = 16.5 J/kgK@50 kOe) and adiabatic temperature change (ΔT〈sub〉ad〈/sub〉 = 8.2 K). Furthermore, short-range ferromagnetic correlation above T〈sub〉N〈/sub〉 contributes to the widening of −ΔS〈sub〉M〈/sub〉 and ΔT〈sub〉ad〈/sub〉 peaks as well as the increase of the ErCoSn compound refrigerant capacity. The results indicate attractive properties of this compound for magnetic refrigeration at cryogenic temperatures.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 492〈/p〉 〈p〉Author(s): C.E. Zaspel〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The dynamic properties of magnetic vortices in single nanopillars, such as the gyrotropic orbital radius and frequency, have been shown to be well-modeled by the Thiele equation. Similarly, a set of coupled Thiele equations also describe synchronization of two or more interacting free layer vortices. Here the Thiele equations are used to model vortex dynamics in linear chains of alternating radius (where nearest-neighbor free layer have different radii) free layer oscillators, which is a system of interacting non-identical oscillators that can synchronize and lock onto a common frequency. For vortices interacting as magnetic dipoles it is shown that there are critical nanopillar separations below which the oscillator chain will synchronize. As the nanopillar separation increases, it is noticed that there is a narrow region of parameter space where synchronization is temporarily lost owing to phase slips and at larger separation synchronization is lost completely. The relation between the critical separation and the free layer radii difference is also estimated analytically.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 492〈/p〉 〈p〉Author(s): Fei Huang, Wenxu Zhang, Bin Peng, Wanli Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We present a method to directly obtain the pure inverse spin Hall effect (ISHE) signal without the spin rectification effect (SRE) signal in ferromagnetic metal(FM)/nonmagnetic metal(NM) bilayers. This method is based on a fact that the distribution of the induced microwave current is largely dependent on the geometries of the samples. The ISHE signal can be maximized through shaping the samples and tuning the magnetic field directions, while the SRE signal can be minimized below the detection limit. This provides also a fast and simplified method to measure the ISHE signal in a wide frequency range. The spin Hall angle of Ta in a Py/Ta bilayer is −0.027 ± 0.015 in a wide frequency range.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 492〈/p〉 〈p〉Author(s): Wu Liu, Weiping Zhang, Wenyuan Chen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The diamagnetically levitated electrostatic micromotor (DLEM), in which five degree of freedom of the levitated pyrolytic graphite rotor are stabilized by permanent magnets except its rotational degree of freedom around the main axis, was studied. The DLEMs were fabricated by using Micro-Electro-Mechanical Systems (MEMS) process and precision machining. The levitation properties of DLEM, which have been analyzed by the finite-element method (FEM) software Ansoft Maxwell 3D, were proved by the levitation experiments. Based on our designed measurement and control system, we successfully realized the continuous operation of the axial variable-capacitance motor by open-loop and closed-loop control. For DLEM1 device, under the fixed frequency and variable frequency open-loop logic with driving voltage of 43 V in air, the achieved rotational speed is 15.4 r/min and 70.0 r/min, respectively. For DLEM2 device, under the variable frequency open-loop and closed-loop control with driving voltage of 30 V in air, the achieved rotational speed is 46.9 r/min and 26.8 r/min, respectively. Experimental results show that the motor presents high reliability under the closed-loop rotational control.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 European Polymer Journal, Volume 119〈/p〉 〈p〉Author(s): Mostafa Khoshsefat, Abbas Dechal, Saeid Ahmadjo, S. Mohammad M. Mortazavi, Gholamhossein Zohuri, Joao B.P. Soares〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We designed a series of dinuclear structures (F〈sub〉1〈/sub〉–F〈sub〉5〈/sub〉) bearing different linkers (rigid to flexible) between the Fe centers to investigate that how they could control the catalyst behaviour and polymer properties. The dinculear structures were used for polymerization of ethylene in presence of MMAO and TiBA. Based on initial results, catalyst F〈sub〉2〈/sub〉 containing methyl-substituted phenyl bridge owned the highest activity (4.9 × 10〈sup〉6〈/sup〉 g PE/mol Fe.h) through dinuclearity and optimum bulkiness among the structures studied. This performance was along with the greatest crystallinity (χ〈sub〉c〈/sub〉) of PE made by the catalyst. Polymerization at higher temperature and monomer pressure exhibited high thermal stability and performance of catalyst F〈sub〉2〈/sub〉, respectively. For further structures, decreasing of effective electronic and steric features led to lower activity. In addition, not only catalyst F〈sub〉4〈/sub〉 bearing the short ethylene bridge exhibited the lowest productivity, but also produced the PE containing high level of short chain branches (37.2 SCB/1000C) affording a branched microstructure of polyethylene in presence of TiBA. It could attribute to low steric and electronic effects and short distance between the centers (ethylene linker) that made it suitable and active for SCB formation. Regarding to it, the electrophilicity index (ω) of F〈sub〉4〈/sub〉 also was greater that led to high capacity or propensity of the specie to accept the (macro) monomer. For this sample, virtually no χ〈sub〉c〈/sub〉 observed in DSC and SSA thermograms. Moreover, MMAO acted as an effective cocatalyst in comparison to TiBA, according to the kinetic profiles of ethylene polymerization. The observations were in respect of strength and affinity of the cocatalysts in deactivation and reactivation of the centers at prolonged time.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0014305719312078-ga1.jpg" width="355" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 492〈/p〉 〈p〉Author(s): Yan Liu, Xiaohong Huo, Shengjie Xuan, Huan Yan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Magnetic skyrmions are swirling nanometric spin textures, which have attracted extensive attention by virtue of their potential applications as information carriers for future memory technology and spintronic devices. Here, we investigate the effect of strain gradient on the in-plane current-driven motion of magnetic skyrmion in a nanotrack. It is found that a longitudinal strain gradient will induce a transverse velocity with its value linearly proportional to the strain gradient. As well, we find that skyrmions can be accelerated or decelerated by the boundary of nanotrack. This behavior depends on the repulsive force induced by boundary and the topological number of skyrmion. Our results not only explain the effect of strain gradient, but also show the influence of the boundary on the skyrmion motion. This work may provide a guide for designing and developing the racetrack memory based on magnetic skyrmions.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 492〈/p〉 〈p〉Author(s): Li Zhang, Yu Feng, Yilin Han, Tie Yang, Xiaotian Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Several 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mrow〉〈mi〉R〈/mi〉〈mover accent="true"〉〈mrow〉〈mn〉3〈/mn〉〈/mrow〉〈mrow〉〈mo stretchy="false"〉¯〈/mo〉〈/mrow〉〈/mover〉〈mi〉c〈/mi〉〈/mrow〉〈/math〉 Dirac half-metallic materials have been proposed and investigated based on first principles. A certain energy value in one spin channel with a clear band gap in the other spin channel leads to the half-metallic properties of these materials and multiple linear band dispersions (Dirac-like crossings) around the Fermi level for fast and low energy consumption electron transmission. In this work, a material synthesized in a prior experiment, PrNiO〈sub〉3〈/sub〉, was found to be a novel half-metallic material with multiple Dirac-like band dispersions according to the first principles. In this work, four magnetic states, i.e., ferromagnetic (FM), nonmagnetic (NM), and antiferromagnetic (AFM-1 and AFM-2) were considered in the 1 × 1 × 1 unit cell of PrNiO〈sub〉3〈/sub〉. Two cases of superlattices, 1 × 1 × 2 and 2 × 2 × 1, were built to study the most stable magnetic state of these systems. We found that the FM is the most stable magnetic state for the 1 × 1 × 1, 1 × 1 × 2, and 2 × 2 × 1 systems. The effects of uniform strain, hole and electron doping, and spin-orbit coupling on its electronic structures were discussed in detail. We hope this work can encourage more experimental and theoretical research on 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mrow〉〈mi〉R〈/mi〉〈mover accent="true"〉〈mrow〉〈mn〉3〈/mn〉〈/mrow〉〈mrow〉〈mo stretchy="false"〉¯〈/mo〉〈/mrow〉〈/mover〉〈mi〉c〈/mi〉〈/mrow〉〈/math〉-type half-metallic materials with multiple Dirac-like band dispersions.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 492〈/p〉 〈p〉Author(s): W. Wang, X.C. Kan, X.S. Liu, C.C. Liu, K.M.U. Rehman, M. Shezad, Q.Y. Wu, S.Q. Zhou, Y.Y. Wang, Z. Wazir〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The critical behavior of the antiperovskite crystal Fe〈sub〉3.4〈/sub〉In〈sub〉0.6〈/sub〉N has been systematically studied in this paper. We have used a modified Arrott plot, the Kouvel-Fisher method, and critical isotherm analysis to obtain the critical exponents (〈em〉β〈/em〉, 〈em〉γ〈/em〉 and 〈em〉δ〈/em〉) which suggest that a long-range magnetic coupling described by mean-field (MF) theoretical model is dominant in Fe〈sub〉3.4〈/sub〉In〈sub〉0.6〈/sub〉N. The experimental 〈em〉M〈/em〉−〈em〉T〈/em〉−〈em〉H〈/em〉 relations below and above Curie temperature (〈em〉T〈/em〉〈sub〉c〈/sub〉) collapse into two branches by the single scaling equation 〈em〉m〈/em〉 = 〈em〉f〈/em〉〈sub〉±〈/sub〉(〈em〉h〈/em〉) (〈em〉m〈/em〉 and 〈em〉h〈/em〉 are renormalized magnetization and field), respectively. The critical exponents are confirmed by the Widom scaling law 〈em〉δ〈/em〉 = 1 + 〈em〉γβ〈/em〉〈sup〉−1〈/sup〉. In addition, it is suggested that the ferromagnetic (FM), anti-ferromagnetic (AFM) interactions and the magnetic disorders result to the exchange distance which is obtained just as 〈em〉J〈/em〉(〈em〉r〈/em〉)∝〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si2.svg"〉〈mrow〉〈msup〉〈mrow〉〈mi〉r〈/mi〉〈/mrow〉〈mrow〉〈mo〉-〈/mo〉〈mn〉4.4〈/mn〉〈/mrow〉〈/msup〉〈/mrow〉〈/math〉.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 492〈/p〉 〈p〉Author(s): Syed Ismail Ahmad, Abdul Rauf, Tasneem Mohammed, Amal Bahafi, D. Ravi Kumar, Madireddy Buchi Suresh〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, we report frequency and temperature dependent dielectric, electrochemical impedance and low temperature magnetic properties of Sol-gel auto-combustion synthesized rare-earth (Ce and Sm) co-substituted cobalt ferrite, CoCe〈sub〉x〈/sub〉Sm〈sub〉y〈/sub〉Fe〈sub〉2-x-y〈/sub〉O〈sub〉4〈/sub〉 (x = y = 0.00, 0.1, 0.12 and 0.25). The surface morphology and particle size as obtained by XRD studies was confirmed by HRTEM measurements for a representative sample. The dielectric properties such as dielectric constant, loss tangent and AC conductivity have been measured using LCR meter, variation of dielectric parameters with substituent concentrations, frequency range from 0.1 to 10 MHz at room temperature (RT) and temperatures 100–400 °C have been well supported by Maxwell-Wagner interfacial polarization. The AC conductivity increased with applied frequency suggesting that the conduction mechanism is owing to small polaron hopping between cations. Impedance studies shows that, the addition of RE (Ce and Sm) cause a decrease in the Z′ value, with increasing frequency which can be attributed to the space charge polarization effect in the material. Low temperature magnetic measurements in ZFC-FC mode and magnetic isotherms at 20 and 310 K reveals the ferromagnetic nature of RE (Ce, Sm) substituted cobalt ferrite nano particles. The coercive field has been increased at low temperature 20 K compared to that at 310 K, the samples shows super paramagnetism beyond room temperature.〈/p〉〈/div〉 〈/div〉