ALBERT

Description: 〈p〉Publication date: 15 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 474〈/p〉 〈p〉Author(s): Muhammad Arshad, M. Asghar, Muhammad Junaid, Muhammad Farooq Warsi, M. Naveed Rasheed, M. Hashim, M.A. Al-Maghrabi, Muhammad Azhar Khan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study Co-Ni co-doped nanocrystalline manganese ferrites were fabricated via co-precipitation method. The annealing of as prepared nanoferrites was done at 950 °C for 7 h. The powder X-ray diffraction (XRD) confirmed that all samples possessed cubic spinel structure. The crystallite size was determined by Scherrer’s equation that lies in the range of 27–35 nm. The spectral analysis confirmed bending and stretching of bonds at octahedral (B) and tetrahedral (A) sites. The spectral bands were shifted towards the longer wavelength side and these indicate the incorporation of dopants cations (Co-Ni). The magnetic parameters were measured from the M-H loops of nanoferrites. With the increase of Co-Ni contents, the saturation magnetization (Ms) increased up to x = 0.15 and then it decreased. The dielectric properties of all compositions were studied in 1 MHz–3 GHz range and were discussed in the light of Debye-type reduction phenomenon by following the Koop’s theory. The dielectric and magnetic behavior evaluation suggested that synthesized ferrites are suitable for microwave devices fabrication.〈/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-S0304885318319127-ga1.jpg" width="282" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 474〈/p〉 〈p〉Author(s): Dongyan Zhang, Zhimin Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Ferromagnetic MPB in the Tb〈sub〉x〈/sub〉Dy〈sub〉1−x〈/sub〉Co〈sub〉2〈/sub〉 system was confirmed via both experimental and theoretical research, which demonstrates the simultaneous structural change with ferromagnetic phase transition. According to the ferromagnetic MPB theory, a phenomenological thermodynamic model of Tb〈sub〉x〈/sub〉Dy〈sub〉1−x〈/sub〉Co〈sub〉2〈/sub〉 at Dy-rich side was constructed. The thermodynamic model predicts the behavior of DyCo〈sub〉2〈/sub〉, which is consistent with the experimental value. The phenomenological thermodynamic model based on ferromagnetic MPB could be employed to make a quantitative analysis of magnetostrictive or magnetocaloric materials.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 474〈/p〉 〈p〉Author(s): F.M. Abbasi, I. Shanakhat, S.A. Shehzad〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Entropy generation analysis for peristalsis of nanofluid with temperature dependent viscosity has been carried out. Mathematical formulation is executed using “long wavelength” approximation. Hall effects and Ohmic heating are also included. Arising non-linear equations are solved using Homotopy Perturbation Method. Analytical solutions for temperature, axial velocity, Bejan number and entropy generation are obtained and examined through graphs. Results show that for enhanced values of nanoparticles volume fraction both velocity and temperature decreases. Increasing values of viscosity parameter decreases the temperature. Moreover, entropy generation and Bejan numbers show decreasing behaviors for increase in nanoparticles volume fraction.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 30 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials〈/p〉 〈p〉Author(s): Bang-Qing Li, Yu-Lan Ma, Perumal Sathishkumar〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A coupled nonlinear system is investigated, which describes the nonlinear short-wave propagation in nanoscale saturated ferromagnetic materials. A series of analytic solutions is constructed via Riccati equation mapping method. Furthermore, two types of novel periodically oscillating solitons are observed by choosing the arbitrary function in the soliton solution as trigonometric function and Jacobian elliptic function, respectively. The parameters can be used to control the compression, stretch, oscillating amplitude and frequency of the solitons.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 April 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 475〈/p〉 〈p〉Author(s): X.J. Weng, L.C. Shen, H. Tang, G.P. Zhao, J. Xia, F.J. Morvan, J. Zou〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Coercivity mechanism has been studied intensively and debated for many years in magnetic materials, particularly in permanent magnets where defects play important roles in adjusting the coercivity. Such a role can be manifested in hard/soft multilayers, where the soft layer can be taken as an enlarged soft defect, which normally exists in so-called single-phased permanent magnets. In this paper, hysteresis loops and spin distributions have been obtained based on both three-dimensional (3D) and one-dimensional (1D) micromagnetic methods for SmCo/Fe to reveal the in-depth coercivity mechanism. Two different geometric models have been constructed to mimic the experimental trilayers, in one of which a transition layer between hard and soft layers is adopted, where calculated nucleation fields and coercivity match very well with the experimental data. As the soft layer thickness increases, both nucleation and coercive fields reduce whilst the coercivity mechanism changes from nucleation to pinning. Such a pinning is inherently related to nucleation and has both attributes of traditional nucleation and pinning, called as a hybrid coercivity mechanism here. The thickness-dependent coercivity mechanism obtained in this work agrees perfectly with the experimental data, which is general for all hard/soft composites and can be extended to single-phased permanent magnets where defects are inevitable.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 474〈/p〉 〈p〉Author(s): P.T.T. Le, Mohsen Yarmohammadi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We study the magnon-charged impurity interaction effects on the magnonic heat capacity (MHC) and the Pauli magnetic susceptibility (PMS) of spin-1/2 and spin-3/2 Lieb lattice within the 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si18.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mi〉J〈/mi〉〈/mrow〉〈mrow〉〈mn〉1〈/mn〉〈/mrow〉〈/msub〉〈mo〉-〈/mo〉〈msub〉〈mrow〉〈mi〉J〈/mi〉〈/mrow〉〈mrow〉〈mn〉2〈/mn〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 Heisenberg model in the presence of the Dzyaloshinskii-Moriya interaction (DMI) and the Zeeman magnetic field. In so doing, we use the Green’s function technique and the full self-consistent Born approximation. We found that in the case of 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si19.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mi〉J〈/mi〉〈/mrow〉〈mrow〉〈mn〉1〈/mn〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 Heisenberg model, the MHC and PMS increase (decrease) with impurity concentration for spin-1/2 (spin-3/2), while oscillate (decrease) when coupling constants next-nearest-neighbor (NNN), DMI, and the Zeeman field are taken into account. We have also investigated perturbed MHC and PMS by ascertained impurity for different coupling strengths, resulting in the oscillating (decreasing) behavior with NNN for spin-1/2 (spin-3/2) and a decreasing behavior with DMI and Zeeman magnetic field for both spin-1/2 and spin-3/2. Moreover, magnetic phase transitions in the case of spin-3/2 are established when tuning coupling constants on the non-zero, whilst no magnetic phase transition is observed for spin-1/2 Lieb lattice. Our findings are useful to tune the physical properties of optical lattices subjected to the electric field, magnetic field, and charged impurity.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 April 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 475〈/p〉 〈p〉Author(s): Petr Ostroverkhov, Alevtina Semkina, Aleksey Nikitin, Alexander Smirnov, Daria Vedenyapina, Kseniya Vlasova, Igor Kireev, Mikhail Grin, Vladimir Chekhonin, Alexander Majouga, Maxim Abakumov〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Magnetic nanoparticles are widely used in various fields of biomedicine. They can combine both therapy and diagnostics modalities thus opening many opportunities for their application. In our work, we have evaluated their ability to work as contrast agents for magnetic resonance imagining and drug delivery systems for photosensitizers. We have shown that after formation of human serum albumin retains ability to bind photosensitizers and they do not lose their optical properties. To obtain stable water solution suitable for long term storage we have additionally modified human serum albumin with polyethylene glycol. It was shown that such modification allows to increase overall stability over time.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 474〈/p〉 〈p〉Author(s): S. Vorobiov, D. Tomasova, V. Girman, H. You, E. Čižmár, M. Orendáč, V. Komanicky〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Structural parameters of nanomagnet arrays have been systematically adjusted in order to study and to maximize the magnetocaloric effect. Optimum technological parameters were experimentally established and arrays of nanomagnets based on Ni〈sub〉3〈/sub〉Pt nanoparticles with a different structure period (1, 2, 3 μm) and two different heights (1.2 and 1.9 μm) were fabricated using electron-beam lithography followed by electrodeposition. The obtained arrays have a phase composition of fcc-Ni〈sub〉3〈/sub〉Pt, which remains unchanged after annealing. It was shown that a change in the period of the nanomagnet arrays leads to a change in the magnitude of the magnetocaloric effect and the operating temperature range. Also, changes in the height of nanomagnets from 1.2 to 1.9 μm lead to an increase in the magnetocaloric response by more than 30%.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 474〈/p〉 〈p〉Author(s): T.J. Hicks, T. Keller, A.R. Wildes〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Neutron resonant spin echo spectroscopy has been applied to measure the splitting of the magnon bands due to the magnetic dipole interaction in the two dimensional antiferromagnet MnPS〈sub〉3〈/sub〉. The splittings measured are more than two orders of magnitude smaller than energies of the magnons. Simulation of the magnon energies involving the calculation of the magnetic dipole interaction in MnPS〈sub〉3〈/sub〉 predict splittings a little higher than those measured. The comparison confirms that the magnetic dipole interaction provides most of the anisotropy which stabilises the antiferromagnetic order in MnPS〈sub〉3.〈/sub〉 We present the first evidence for the splitting of magnon bands due to the magnetic dipole interaction in a two dimensional antiferromagnet.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 474〈/p〉 〈p〉Author(s): A.H. Gevorgyan, S.S. Golik, T.A. Gevorgyan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The peculiarities of transmission and angular non-reciprocity in magneto-photonic crystals (MPC) are investigated. The problem of light transmission through magneto-photonic crystal is solved by Ambartsumian’s modified layer addition method. It is shown that the system under consideration can work as a wide band ideal optical diode for orthogonal circular polarizations and as a narrow band ideal optical diode for orthogonal linear polarizations. The influence of the magnitude of external static magnetic field, its direction, and the angle of incidence on the diode properties are investigated.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): Jun He, Lianwen Deng, Heng Luo, Longhui He, Dongyong Shan, Shuoqing Yan, Shengxiang Huang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Ti〈sub〉3〈/sub〉SiC〈sub〉2〈/sub〉 particles encapsulated by Ni〈sub〉0.5〈/sub〉Zn〈sub〉0.5〈/sub〉Fe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 shell were in-situ synthesized via a facile sol-gel method. Effects of Ni〈sub〉0.5〈/sub〉Zn〈sub〉0.5〈/sub〉Fe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 shell on electromagnetic properties of Ti〈sub〉3〈/sub〉SiC〈sub〉2〈/sub〉 were investigated in 2–18 GHz. Moderated complex permittivity and desirable higher complex permeability presented for the Ni〈sub〉0.5〈/sub〉Zn〈sub〉0.5〈/sub〉Fe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉/Ti〈sub〉3〈/sub〉SiC〈sub〉2〈/sub〉 composite, resulting in strong microwave attenuation ability and good impedance matching property. The measured effective absorbing bandwidth (RL 〈 −10 dB) of 5.3 GHz and corresponding maximum RL of −38.6 dB were obtained for the Ni〈sub〉0.5〈/sub〉Zn〈sub〉0.5〈/sub〉Fe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉/Ti〈sub〉3〈/sub〉SiC〈sub〉2〈/sub〉 absorbing coating of 1.2 mm thickness. These results indicate that the Ni〈sub〉0.5〈/sub〉Zn〈sub〉0.5〈/sub〉Fe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉/Ti〈sub〉3〈/sub〉SiC〈sub〉2〈/sub〉 composite may become a new type of microwave absorbent.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): Weikai Lei, Qingzheng Jiang, Sajjad Ur Rehman, Lunke He, Xianjun Hu, Qingwen Zeng, Qiulan Tan, Renhui Liu, Minglong Zhong, Zhenchen Zhong〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The expensive rare earth elements Nd, Pr, Dy and Tb have been extensively used for making NdFeB-based magnets, but the less expensive and high abundant rare earth (HARE) elements such as La and Ce have been over stocked. The marketing expansion of the HARE elements is of much interest in academia and industry to achieve effective and efficient utilization of HARE elements. In this paper, nanocrystalline (Nd〈sub〉1−〈/sub〉〈em〉〈sub〉x〈/sub〉〈/em〉La〈em〉〈sub〉x〈/sub〉〈/em〉)〈sub〉13〈/sub〉Fe〈sub〉81〈/sub〉B〈sub〉6〈/sub〉 (〈em〉x〈/em〉 = 0–0.5) alloys were fabricated by melt-spinning method. It is found out that the room temperature magnetic properties of the alloys decrease sharply when La is substituted for Nd up to 20 at.%. However, an anomalous increase in 〈em〉J〈/em〉〈sub〉r〈/sub〉 value and improved thermal stability of the alloy ribbons are observed for 40 at.% La substituted alloy while the reduction in magnetic properties is only nominal up to 30 at.%. Furthermore, the Curie temperature decreases from 588 K to 561 K with 50 at.% La substitution, which is higher than the equal amount of Ce substitution in Nd-Fe-B. It is shown by the Henkel curves that the alloy with 40 at.% La has the biggest value of positive peak which demonstrates the strongest exchange coupling in the 40 at.% La substituted alloy. The TEM micrographs indicate that the alloy containing 40 at.% La has more uniform and refined microstructure resulted in the enhanced properties.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 472〈/p〉 〈p〉Author(s): A.R. Moura, R.J.C. Lopes〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We used the Self-Consistent Harmonic Approximation (SCHA) to study the thermodynamics of the precession magnetization in a two-dimensional isotropic ferromagnet. The SCHA treats the Hamiltonian in terms of the canonically conjugate operators 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si10.gif" overflow="scroll"〉〈mrow〉〈msup〉〈mrow〉〈mi〉S〈/mi〉〈/mrow〉〈mrow〉〈mi〉z〈/mi〉〈/mrow〉〈/msup〉〈/mrow〉〈/math〉 and 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si11.gif" overflow="scroll"〉〈mrow〉〈mi〉φ〈/mi〉〈/mrow〉〈/math〉 (the azimuth angle) including renormalized temperature dependent parameters to take into account higher order interactions. It is well-known that in right conditions, a dynamic magnetic field is able to provide spin pumping and drives the system to a magnon Bose-Einstein condensation. The magnon condensate is a coherent state that presents minimal uncertainty for the 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si10.gif" overflow="scroll"〉〈mrow〉〈msup〉〈mrow〉〈mi〉S〈/mi〉〈/mrow〉〈mrow〉〈mi〉z〈/mi〉〈/mrow〉〈/msup〉〈/mrow〉〈/math〉 and 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si11.gif" overflow="scroll"〉〈mrow〉〈mi〉φ〈/mi〉〈/mrow〉〈/math〉 operators. Consequently, 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si14.gif" overflow="scroll"〉〈mrow〉〈mo stretchy="true"〉〈〈/mo〉〈msup〉〈mrow〉〈mi〉S〈/mi〉〈/mrow〉〈mrow〉〈mi〉z〈/mi〉〈/mrow〉〈/msup〉〈mo stretchy="true"〉〉〈/mo〉〈/mrow〉〈/math〉 and 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si15.gif" overflow="scroll"〉〈mrow〉〈mo stretchy="true"〉〈〈/mo〉〈mi〉φ〈/mi〉〈mo stretchy="true"〉〉〈/mo〉〈/mrow〉〈/math〉 should constitute natural fields to describe the model, which justifies the SCHA formalism. The results obtained are consistent with other theoretical and experimental works.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): T. Bartoli, K. Zehani, J. Moscovici, A. Michalowicz, L. Bessais〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Nanocrystalline 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si115.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mtext〉PrCo〈/mtext〉〈/mrow〉〈mrow〉〈mn〉3〈/mn〉〈mo〉-〈/mo〉〈mi〉x〈/mi〉〈/mrow〉〈/msub〉〈msub〉〈mrow〉〈mtext〉Fe〈/mtext〉〈/mrow〉〈mrow〉〈mi〉x〈/mi〉〈/mrow〉〈/msub〉〈mo stretchy="false"〉(〈/mo〉〈mi〉x〈/mi〉〈mo〉⩽〈/mo〉〈mn〉1〈/mn〉〈mo stretchy="false"〉)〈/mo〉〈/mrow〉〈/math〉 powder samples were synthesized by high energy milling and subsequent annealing at 1023 K for 30 min. The samples crystallize in the 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mtext〉PuNi〈/mtext〉〈/mrow〉〈mrow〉〈mn〉3〈/mn〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉-type structure (space group 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si3.gif" overflow="scroll"〉〈mrow〉〈mi〉R〈/mi〉〈mover accent="true"〉〈mrow〉〈mn〉3〈/mn〉〈/mrow〉〈mrow〉〈mo〉¯〈/mo〉〈/mrow〉〈/mover〉〈mi〉m〈/mi〉〈/mrow〉〈/math〉) for 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si118.gif" overflow="scroll"〉〈mrow〉〈mi〉x〈/mi〉〈mo〉〈〈/mo〉〈mn〉1〈/mn〉〈/mrow〉〈/math〉, confirmed by means of X-ray diffraction. In order to explain the original magnetic properties of these compounds and for the determination of the exchange interaction in theoretical models, the Fe and Co sites and occupancies in the crystallographic structures are required. However, standard XRD can not be used to determine Fe substitution sites, because Co and Fe have too close X-ray atomic scattering factors. Results from neutron diffraction and electronic band structure calculations from our previous works were incomplete or limited. Consequently, we give in this study the characterization of the local structure by X-ray absorption spectroscopy (EXAFS) at the iron K edge. By this method, and if we assume a unique preferential site, it was determined that Fe atoms preferably occupy the 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si15.gif" overflow="scroll"〉〈mrow〉〈mn〉18〈/mn〉〈mi〉h〈/mi〉〈/mrow〉〈/math〉 site. In order to obtain this result, a coordination sphere around Fe sites of 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si120.gif" overflow="scroll"〉〈mrow〉〈mi〉R〈/mi〉〈mo〉=〈/mo〉〈mn〉5.2〈/mn〉〈/mrow〉〈/math〉 Åhad to be considered in order to find sufficient local differences between the possible sites (〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si15.gif" overflow="scroll"〉〈mrow〉〈mn〉18〈/mn〉〈mi〉h〈/mi〉〈/mrow〉〈/math〉, 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si14.gif" overflow="scroll"〉〈mrow〉〈mn〉6〈/mn〉〈mi〉c〈/mi〉〈/mrow〉〈/math〉 and 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si53.gif" overflow="scroll"〉〈mrow〉〈mn〉3〈/mn〉〈mi〉b〈/mi〉〈/mrow〉〈/math〉). Furthermore, we provide complementary magnetic properties measurements for 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si4.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mtext〉PrCo〈/mtext〉〈/mrow〉〈mrow〉〈mn〉3〈/mn〉〈mo〉-〈/mo〉〈mi〉x〈/mi〉〈/mrow〉〈/msub〉〈msub〉〈mrow〉〈mtext〉Fe〈/mtext〉〈/mrow〉〈mrow〉〈mi〉x〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 (〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si125.gif" overflow="scroll"〉〈mrow〉〈mi〉x〈/mi〉〈mo〉⩽〈/mo〉〈mn〉0.75〈/mn〉〈/mrow〉〈/math〉) such as the coercive field 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si106.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mtext〉H〈/mtext〉〈/mrow〉〈mrow〉〈mi〉C〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉, which decreases with iron content from 12 kOe for 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si127.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mtext〉PrCo〈/mtext〉〈/mrow〉〈mrow〉〈mn〉3〈/mn〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 to 1.5 kOe for 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si128.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mtext〉PrCo〈/mtext〉〈/mrow〉〈mrow〉〈mn〉2.25〈/mn〉〈/mrow〉〈/msub〉〈msub〉〈mrow〉〈mtext〉Fe〈/mtext〉〈/mrow〉〈mrow〉〈mn〉0.75〈/mn〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉. The magnetization at saturation 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si17.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mtext〉M〈/mtext〉〈/mrow〉〈mrow〉〈mi〉S〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 increases from 69 A m〈sup〉2〈/sup〉/kg to 89 A m〈sup〉2〈/sup〉/kg and the calculated anisotropy field 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si18.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mtext〉H〈/mtext〉〈/mrow〉〈mrow〉〈mi〉a〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 decreases from 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si131.gif" overflow="scroll"〉〈mrow〉〈mn〉15.6〈/mn〉〈/mrow〉〈/math〉 kOe to 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si132.gif" overflow="scroll"〉〈mrow〉〈mn〉11.2〈/mn〉〈/mrow〉〈/math〉 kOe for the same compositions.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): Oznur Karaagac, Hakan Köçkar〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, Taguchi method, response surface methodology and regression analyses have been applied to assess the effects of synthesis parameters on saturation magnetisation, M〈sub〉s〈/sub〉 of iron nanoparticles produced by hydrogen reduction of iron oxide nanoparticles. The M〈sub〉s〈/sub〉 values were obtained from the magnetisation loops measured by a vibrating sample magnetometer. Structural characterisations of the selected samples were done by X-ray diffraction technique and transmission electron microscopy. Orthogonal array L9 with three parameters (temperature, reaction time and H〈sub〉2〈/sub〉 flow rate) at three levels (low, medium and high) was used to obtain the experimental trials. Based on the signal to noise (S/N) ratio considering the condition larger is the better approach and the mean response, the highest M〈sub〉s〈/sub〉 condition has been found when the temperature is 800 °C m/min, reaction time is 60 min and H〈sub〉2〈/sub〉 flow rate is 1000 ml/min. Analysis of Variance (ANOVA) is applied to find out the F-ratio and percentage contribution of each parameter by using experimental trials and S/N ratios. It was found that the temperature was the most significant parameter on the M〈sub〉s〈/sub〉 of iron nanoparticles. A confirmation experiment has been carried out by using the experimental conditions obtained from Taguchi method. The M〈sub〉s〈/sub〉 of the optimum sample was found to be 217.42 emu/g which was within 95% confidence level with the predicted optimal M〈sub〉s〈/sub〉 of 214.03 emu/g. The quality losses for M〈sub〉s〈/sub〉 obtained at the highest combinations were 70.7%. In addition, analyses of multiple linear and quadratic regressions were employed to derive the predictive equations of the M〈sub〉s〈/sub〉 achieved via experimental design. The predicted values from the developed models and experimental values are found to be very close to each other justifying the significance of the models. Besides, the quadratic interactive regression model provided the best statistical performance with high R〈sup〉2〈/sup〉 and R〈sup〉2〈/sup〉(adj) values of 100 and 100%, respectively between the experimental and predicted values of M〈sub〉s〈/sub〉. More intensive predicted values were obtained by the quadratic regression models as compared to the multiple linear regression models. Taguchi prediction method was also very successful in the optimization of synthesis parameters for the highest M〈sub〉s〈/sub〉 of nanoparticles within the prescribed limit.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): L. Balejčíková, V.I. Petrenko, M. Baťková, K. Šipošová, V.M. Garamus, L.A. Bulavin, M.V. Avdeev, L. Almásy, P. Kopčanský〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Presence of protein amyloid aggregates is associated with many neurodegenerative disorders, such as Alzheimer’s disease etc. The effect of magnetoferritin and reconstructed ferritin on the structure of lysozyme amyloid aggregates was studied using small-angle X-ray scattering, atomic force microscopy and thioflavin T fluorescence measurements. It has been shown that both magnetoferritin and reconstructed ferritin molecules affect the size, structure and amount of the amyloid fibrils. We assume that the anti-amyloid effect of magnetoferritin and reconstructed ferritin is due to the presence of iron in solutions but is not associated with the magnetic character of the iron oxide phases, i.e. magnetite/maghemite for magnetoferritin and ferrihydrite for ferritin.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 5 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials〈/p〉 〈p〉Author(s): Philipp Lemal, Sandor Balog, Christoph Geers, Patricia Taladriz-Blanco, Andrea Palumbo, Ann M. Hirt, Barbara Rothen-Rutishauser, Alke Petri-Fink〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Magnetic hyperthermia for cancer treatment has gained significant attention in recent years, due to its biocompatibility of applied nanoparticles and the possibility for spatially localized heating in deep tissues. Clinical treatments use nanoparticle concentrations of 112 mg Fe/mL, while the concentrations experimental studies have addressed are considerably smaller, usually between 0.1 and 30 mg/mL. Therefore, it is not clear whether such experiments correspond to the magnetic properties found in clinical applications. In this regard, we studied the thermal behavior of superparamagnetic iron oxide nanoparticles (SPION) with the most common particle shapes used in the field, including spherical (core diameters 11 and 19 nm), cubic (15 nm) and ellipsoidal (23 nm with an aspect ratio of 1.45), at concentrations ranging from 5 to 80 mg Fe/mL. Their shape, size, crystallinity, magnetic, and thermal behavior were characterized via transmission electron microscopy, dynamic light scattering, Taylor dispersion analysis, X-ray diffraction, alternating gradient magnetometry, and lock-in thermography. Spherical and cubic nanoparticles displayed linear heating slopes, independent from size, shape and concentration, resulting in unchanged specific absorption rates (SAR). Ellipsoids showed the same behavior until 50 mg/mL, above which a decreasing heating slope trend was found, without evidence as to what causes this behavior. However, the presented results highlight the importance of colloidally stable SPIONs in magnetic hyperthermia to obtain maximum heating power by minimum particle dosage.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): Peerasak Chantngarm, Bumned Soodchomshom〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We study pressure control of transport properties in graphene-based FM/B/FM junction where FMs are ferromagnetic graphene regions and B is graphene/MoS〈sub〉2〈/sub〉 heterostructure barrier. In graphene/MoS〈sub〉2〈/sub〉 heterostructure region, the Fermi energy has been found to be linearly pressure-dependent. Therefore, it is possible to control the currents by pressure in the presented structure. In non-magnetic junction, it was found that, the charge current depends almost linearly on pressure near the Dirac point. We find that the Dirac point can be shifted by varying back gate potential. The correlation between current and pressure in the junction may lead to applications for pressure sensors and pressure transistors. In magnetic junction, we predicted that the switching of spin polarization may occur at a specific pressure and spin current may be linearly controlled by pressure near the Dirac point. The results reveal the potentials of graphene/MoS〈sub〉2〈/sub〉 heterostructure for applications in pressure-controlled charge current and spin current devices.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): Oznur Karaagac, Busra Bilir Yildiz, Hakan Köçkar〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, superparamagnetic cobalt ferrite nanoparticles (SCFNs) were synthesized by co-precipitation in one-step. The synthesis parameters; reaction time and stirring rate, were varied separately while the other parameters were fixed constant to investigate the effect of the parameters on the properties of SCFNs. X-ray diffraction analysis and Fourier transform infrared spectroscopy confirmed that synthesized samples are cobalt ferrite. The magnetization consistently increased with the particle size as the reaction time increased and the stirring rate decreased. While the reaction time was effective on the size of the cobalt ferrite nanoparticles, the stirring rate was also found to have influence on the particle size and thus the magnetization of the nanoparticles. The critical size of cobalt ferrite nanoparticles for superparamagnetic limit with zero coercivity and remanence was found to be around 7 nm and its maximum magnetization value was 41.0 emu/g. When the size of the SCFNs went over 7 nm, the magnetization increased with a small coercivity of 2–5 Oe, which may offer a potential usage in magnetic hyperthermia applications. It was seen that structural properties, especially the particle sizes and corresponding magnetic properties of SCFNs were considerably affected by the parameters of stirring rate and especially reaction time. Therefore, it is seen that SCFNs with desirable properties can be tailored by changing the synthesis parameters and therefore may have the potential to use in biomedical applications.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): Marina Mühlberger, Christina Janko, Harald Unterweger, Eveline Schreiber, Julia Band, Christian Lehmann, Diana Dudziak, Geoffrey Lee, Christoph Alexiou, Rainer Tietze〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉According to the World Health Organization, cancer is the second most important cause of death in Europe. Due to its manifold manifestations, it is not possible to treat all patients according to a uniform scheme. However, all solid tumors have one thing in common: independent of the tumor’s molecular subgroup and the treatment protocol, the immune status of the tumor, especially the amount of tumor infiltrating lymphocytes (TILs), is important for the patient’s clinical outcome – the higher the number of TILs, the better the outcome. For this reason it seems desirable to increase the number of TILs.〈/p〉 〈p〉One way to accumulate T cells in the tumor area is to make them magnetizable and attract them with an external magnetic field. Magnetization can be achieved by superparamagnetic iron oxide nanoparticles (SPIONs) which can be bound to the cells’ surface or internalized into the cells.〈/p〉 〈p〉For this study, SPIONs with different coatings were synthesized and incubated with immortalized mouse T lymphocytes. SPIONs only stabilized with lauric acid (LA) coated 〈em〉in situ〈/em〉 or afterwards showed high toxicity. Addition of an albumin layer increased the biocompatibility but reduced cellular uptake. To increase the cellular uptake the albumin coated particles were aminated, leading to both higher uptake and toxicity, dependent on the degree of amination. In the presence of an externally applied magnetic field, T cells loaded with selected types and amounts of SPIONs were guidable.〈/p〉 〈p〉With this promising pilot study we already can demonstrate that it is possible to attract SPION bearing T cells by an external magnet.〈/p〉 〈p〉To sum up, biocompatibility and uptake of SPIONs by T cells are opposing events. Thus, for the functionalization of T cells with SPIONs the balance between uptake and toxicity must be evaluated carefully.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 30 August 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials〈/p〉 〈p〉Author(s): Azhar Ali Zafar, Nehad Ali Shah, Ilyas Khan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this paper, two-phase flow of blood is considered through a circular tube along with magnetic properties. The tube is considered as a circular cylinder form and the blood is flowing through it under the influence of uniform magnetic field and an external oscillating pressure gradient. Exact solutions for the fluid and magnetic particles velocities are obtained by means of integral transforms. The velocity of the fluid is presented as a sum of post transient and transient solutions. Moreover, a semi-analytical solution based on the Bessel equation and Tzou’s algorithm for the inverse Laplace transform is obtained. A comparison among the profiles of the fluid’s velocity determined with both solutions is also made. Furthermore, in order to study the influence of the material parameters, numerical simulations and graphical illustrations are used and useful conclusions are summarized.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): I.R. Souza Filho, M.J.R. Sandim, R. Cohen, L.C.C.M. Nagamine, H.R.Z. Sandim, D. Raabe〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Strain-induced martensite (SIM) formation was evaluated upon cold-rolling of a 17.6 wt.%Mn-TRIP steel by means of magnetic measurements, X-ray diffraction, and high-resolution electron backscatter diffraction (EBSD). α′-martensite formation was observed to be dependent on the presence of prior ε-martensite. Upon deformation, the coercivity of the ferromagnetic α′-martensite is characterized by strong magnetic shape anisotropy. Austenite (γ) reversion was evaluated by means of in situ magnetic measurements during continuous annealing. The experimental results were compared to thermodynamic simulations. It turned out that γ-reversion was not completed in the regime where a γ-single phase field is expected, which suggests the splitting of α′ → γ transformation into two stages. The Curie temperature of remaining α′-martensite was determined as being ∼620 °C. Magnetic properties presented an annealing time-dependence within the temperature range of 500–600 °C, suggesting long-range diffusional α′ → γ transformation. With the aid of electron channeling contrast image technique (ECCI), we noticed that the formation of γ-nanograins in the early stages of reversion is sufficient to induce strong magnetic shape anisotropy in this steel. After full austenitization at 800 °C, further 〈em〉in〈/em〉 situ magnetic measurements were also used to track the magnetic response of the material upon controlled cooling. Athermal formation of α′-martensite within the prior athermal ε-phase was clearly observed for temperatures lower than 100 °C. Using thermodynamic modeling we also calculated the start temperature for ε-formation (〈em〉M〈sub〉s〈/sub〉〈/em〉〈sup〉ε〈/sup〉). Results showed that ε-martensite is indeed expected to form before α′, which was confirmed in all cases by means of EBSD.〈/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-S0304885318318948-ga1.jpg" width="301" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 472〈/p〉 〈p〉Author(s): D. Kostopoulos, I. Panagiotopoulos〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Finite element micromagnetics are used to simulate remanence, hysteresis and dynamic switching in crescent shaped permalloy caps, a geometry that corresponds to either normal or oblique deposition of films on nanosphere arrays. Oblique deposition breaks the symmetry and favours onion states rather than vortices. It introduces in-plane shape anisotropy analogous to that of an elongated island and increases the in-plane coercivity. In isolated caps, the critical diameter above which the vortex state is the minimum energy state, is 〈em〉D〈/em〉 = 123 nm for angles below θ = 20 deg. It increases with θ up to a vlaue of 〈em〉D〈/em〉 = 157 nm at θ = 45 deg. Even for sizes for which the onion state is the lowest energy state, vortex states can be stabilized in isolated caps but the interparticle magnetostatic interactions tend to destabilize them driving the system to its ground state. The switching field of onion states can be reduced by 36% using microwave resonance at frequencies approaching the resonant (Kittel mode) frequencies.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): Gaurav Vats, Ravikant, Shalini Kumari, Dhiren K. Pradhan, Ram S. Katiyar, V.N. Ojha, Chris R. Bowen, Ashok Kumar〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This study reports the magnetocaloric effect (MCE) and piezoresponse of integrated ferroelectric-ferromagnetic heterostructures of PbZr〈sub〉0.52〈/sub〉Ti〈sub〉0.48〈/sub〉O〈sub〉3〈/sub〉 (PZT) (5 nm)/Bi-Sr-Ca-Cu〈sub〉2〈/sub〉-O〈sub〉X〈/sub〉 (BSCCO) (5 nm)/La〈sub〉0.67〈/sub〉Sr〈sub〉0.33〈/sub〉MnO〈sub〉3〈/sub〉 (LSMO) (40 nm)/MgO (0 0 1). Magnetic and pizoresponse behavior of the heterostructures are found to be governed by magneto-electric coupling and induced lattice strains. In addition, a maximum MCE is studied using Maxwell equations from both Field Cooled (FC) and Zero Field Cooled (ZFC) magnetization data. Maximum MCE entropy change (|Δ〈em〉S〈/em〉|) of 42.6 mJkg〈sup〉−1〈/sup〉K〈sup〉−1〈/sup〉 (at 258 K) and 41.7 mJkg〈sup〉−1〈/sup〉K〈sup〉−1〈/sup〉 (at 269 K) are found corresponding to FC and ZFC data, respectively. The variation in maximum entropy change and corresponding temperatures for FC and ZFC data revealed that the application of a magnetic field can significantly contribute towards tuning of the MCE. Interestingly, these multilayered structures are found to sustain MCE over a broad temperature range, which makes them attractive for improved solid-state energy conversion devices.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): Anna C. Bakenecker, Anselm von Gladiss, Thomas Friedrich, Ulrich Heinen, Heinrich Lehr, Kerstin Lüdtke-Buzug, Thorsten M. Buzug〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The untethered actuation of milli- and microdevices is of great interest for a variety of medical applications. A millimeter sized swimmer is shown, which is 3D-printed and coated with magnetic nanoparticles. The coating has to fulfill two requirements: First, it must have a high magnetic moment in order to show a strong reaction to a magnetic field for good actuation performance. Second, it has to be suitable for magnetic particle imaging (MPI). MPI is an emerging medical imaging technique, based on the nonlinear response of superparamagnetic nanoparticles to oscillating magnetic fields. It is aimed at dual use of an MPI scanner: for both actuation and visualization. When applying rotating homogeneous magnetic fields, the swimmer performs an axial movement due to its shape and the viscosity of the surrounding medium. These fields can be generated with an MPI scanner. The swimmer dynamics have been observed and a maximum swimming velocity of 6 mm/s at a rotation frequency of the magnetic field of 10 Hz was found. The experiments are performed with a commercially available preclinical MPI scanner. It is shown, that the swimmer is suitable to be imaged with MPI. Furthermore, sequentially acquired images of a moving swimmer are shown. For this, the MPI scanner was alternately driven in imaging and actuation mode.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): Huarui Fu, Yunlong Li, Li Ma, Caiyin You, Qing Zhang, Na Tian〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The polycrystalline CoFeMnSi alloy with a potential spin gapless semiconductor (SGS) behavior was prepared by arc melting. The structures, magnetism and transport properties of CoFeMnSi alloy were investigated in detail. The occurrence of (1 1 1) superlattice XRD peak indicates the highly ordered Y-type structure of CoFeMnSi alloy. The saturation magnetization is around 3.49 〈em〉μ〈/em〉〈sub〉B〈/sub〉/f.u. and the Curie temperature is about 763 K. The transport properties exhibit a semiconducting-like behavior and the resistivity is about 269 μΩ cm at 300 K. The carrier concentration almost shows a non-dependence of temperature, which is different from that of traditional semiconductor, presenting a typical characteristic of spin gapless semiconductor. The carrier concentration and carrier mobility measured at 300 K are 4.9 × 10〈sup〉20〈/sup〉 cm〈sup〉−3〈/sup〉 and 46 cm〈sup〉2〈/sup〉/V.s, respectively.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 22 September 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials〈/p〉 〈p〉Author(s): V.N. Gaonkar, E.T. Dias, Arka Bikash Dey, Rajendra Prasad Giri, A.K. Nigam, K.R. Priolkar〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this paper we attempt to understand the role of tin and carbon in magnetic interactions in Mn〈sub〉3〈/sub〉SnC. Mn〈sub〉3〈/sub〉SnC exhibits a time dependent magnetic configuration and a complex magnetic ground state with both ferromagnetic and antiferromagnetic orders. Such a magnetic state is attributed to presence of distorted 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si33.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mtext〉Mn〈/mtext〉〈/mrow〉〈mrow〉〈mn〉6〈/mn〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉C octahedra with long and short Mn–Mn bonds. Our studies show that C deficiency increases the tensile strain on the 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si33.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mtext〉Mn〈/mtext〉〈/mrow〉〈mrow〉〈mn〉6〈/mn〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉C octahedra which elongates Mn–Mn bonds and strengthens ferromagnetic interactions while Sn deficiency tends to ease out the strain resulting in shorter as well as longer Mn–Mn bond distances in comparison with stoichiometric Mn〈sub〉3〈/sub〉SnC. Such a variation strengthens both, ferromagnetic and antiferromagnetic interactions. Thus the structural strain caused by both Sn and C is responsible for complex magnetic ground state of Mn〈sub〉3〈/sub〉SnC.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 474〈/p〉 〈p〉Author(s): A. Rathi, P.D. Babu, P.K. Rout, V.P.S. Awana, Vikash K. Tripathi, R. Nagarajan, B. Sivaiah, R.P. Pant, G.A. Basheed〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We present the results of a detailed investigation of magnetism in spinel chromite NiCr〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 magnetic nanoparticles (MNPs). Compared to the bulk NiCr〈sub〉2〈/sub〉O〈sub〉4〈/sub〉, the finite crystallite size of about 10 nm lowers the Jahn-Teller distortion and greatly enhances the collinearity of the spin structure in MNPs with considerably reduced “frustration index” = 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si45.gif" overflow="scroll"〉〈mrow〉〈mo stretchy="false"〉|〈/mo〉〈msub〉〈mrow〉〈mi〉θ〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="normal"〉CW〈/mi〉〈/mrow〉〈/msub〉〈mo stretchy="false"〉|〈/mo〉〈/mrow〉〈/math〉/〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si46.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mi〉T〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="normal"〉c〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉. This leads to (longitudinal) ferrimagnetic ordering at much higher temperature, 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si47.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mi〉T〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="normal"〉c〈/mi〉〈/mrow〉〈/msub〉〈mo〉≈〈/mo〉〈mn〉100〈/mn〉〈/mrow〉〈/math〉 K and suppression of (transverse) antiferromagnetic ordering in MNPs (cf. 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si46.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mi〉T〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="normal"〉c〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si42.gif" overflow="scroll"〉〈mrow〉〈mo〉≃〈/mo〉〈/mrow〉〈/math〉 65 K and 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si50.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mi〉T〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="normal"〉s〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si42.gif" overflow="scroll"〉〈mrow〉〈mo〉≃〈/mo〉〈/mrow〉〈/math〉 30 K in the bulk); a transition to the cluster spin glass state occurs at 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si52.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mi〉T〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="normal"〉g〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 = 19.0 K. Moreover, the M-H hysteresis loops show anomalous “hour-glass” behavior at fields near 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si53.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mi〉H〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="normal"〉c〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 in the vicinity of 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si52.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mi〉T〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="normal"〉g〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉; this non-monotonous 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si53.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mi〉H〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="normal"〉c〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 (T) variation can not be accounted from the celebrated Stoner-Wohlfarth model. The present study interprets the anomalous 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si53.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mi〉H〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="normal"〉c〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 (T) behavior in the framework of magnetically interacting core-shell structure with large surface anisotropy, and points out the importance of surface effects in nanochromites compared to their counterpart ferrites.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): Anna Konopacka, Rafał Rakoczy, Maciej Konopacki〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Bioethanol is a promising liquid biofuel, which can be produced from the wide range of biomass feedstock by the fermentation process with the 〈em〉Saccharomyces cerevisiae〈/em〉 yeast. The application of the rotating magnetic field (RMF) is one of the possibilities to increase the efficiency of the process. Therefore, the magnetically-assisted bioreactor equipped with RMF generator was used to perform the ethanol fermentation process with the sugar-rich medium. Moreover, the yeast cells were modified by addition of Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 nanoparticles. The obtained data suggested that the stimulation of applied cells with RMF did increase the proliferation and the ethanol production process. Furthermore, the calculated maximum specific growth rate and the productivity coefficient showed RMF positive effect on this magnetically-assisted bioprocess. The stimulation was found as ruled by field frequency (connected with magnetic induction of RMF) and it was revealed that the process productivity was higher for experiments with modified cells and the growth rate was higher for the process without the addition of Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 nanoparticles.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): Alimohammad Mesbahinia, Mohammad Almasi-Kashi, Ali Ghasemi, Abdolali Ramezani〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this paper Co〈sub〉1-x〈/sub〉Ni〈sub〉x〈/sub〉Fe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 in which x ranging from 0.0 to 1.0 with 0.2 intervals was prepared with different particle size using a co-precipitation method. A single phase cubic spinel structure with an average crystallite size between 24 and 34 nm was obtained. X-ray diffraction, fourier transform infrared spectroscopy, field emission scanning electron microscopy and vibration sample magnetometer were used to characterize the samples. The energy dispersive X-ray analysis was in good agreement with the nominal composition. It was found that the functional groups of Co-Ni spinel ferrite were formed during the combustion process. It was found that by substitution of nickel cation in cobalt ferrite, the saturation magnetization and the coercivity decreased from 52.70 emu/g and 1673 Oe to 22.11 emu/g and 134 Oe, respectively. First order reversal curves were employed to map the magneto-static interactions and coercivity distributions as a function of nickel concentration. Adding nickel shifts the switching field distribution to the lower field thereby softening the samples. The ratio of reversibility increases with an increase in nickel content due to increase in the percentage of superparamagnetism.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 3 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials〈/p〉 〈p〉Author(s): P. Wongjom, R. Ramos, S. Pinitsoontorn, K. Uchida, E. Saitoh〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Measurements of transverse thermoelectric voltage were carried out in Co〈sub〉40〈/sub〉Fe〈sub〉60〈/sub〉 (CoFe)/Yttrium-Iron-Garnet (YIG) magnetic junctions, using the CoFe film as the spin detector. An unusual dependence of the voltage on the CoFe thickness was observed in the in-plane magnetized (IM) configuration; the junction with a relatively thick CoFe layer (40 nm) exhibits positive signals, whereas the junctions with a thinner CoFe layer (7-10 nm) exhibit negative signals. To find the origin of the behavior, we compare the voltage signals in the CoFe/YIG and CoFe/GGG systems in the IM configuration as well as perpendicularly magnetized (PM) configuration. Furthermore, the anomalous Hall effect was also measured in the Hall-bar shaped CoFe films. The experimental results suggest that the observed thickness dependence of the voltage is attributed to the combination of the inverse spin Hall effect (ISHE) and the anomalous Nernst effect (ANE) in the CoFe layers; the former shows a negative voltage and its contribution gradually increases with decreasing the CoFe thickness, whereas the latter shows a positive and mostly thickness independent voltage. The competition between the ISHE and ANE contributions results in the observed peculiar CoFe-thickness dependence of the transverse thermoelectric voltage.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 472〈/p〉 〈p〉Author(s): Jian Lei, Jingwu Zheng, Haida Zheng, Liang Qiao, Yao Ying, Wei Cai, Wangchang Li, Jing Yu, Min Lin, Shenglei Che〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, we investigated the effects of heat treatment and lubricant on the magnetic properties of iron-based soft magnetic composites by one-pot synthesis method. Scanning electron microscopy (SEM) revealed that the surface of the coated Fe powder was coated with different thickness of Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 insulating layer. The experiment results indicated that using lubricant in the coated iron-based compacts presented higher permeability, higher resistivity, lower core loss over the wide frequency range compared with those without using lubricant after heat treatment at 773 K. The above effects would be reduced with the increase of the thickness of the alumina coating. As the heat treatment temperature raised from 573 K to 773 K and even higher 873 K, zinc stearate continued to decompose, and its decomposition product carbon reacted with the iron oxide of the thinner coating. As a result, the frequency stability of the permeability decreased especially at high frequencies, the resistivity decreased significantly, and the eddy current loss increased significantly. When the alumina insulation layer became thick, the effects of zinc stearate and its leaving carbon after decomposition on the properties of the pressed magnet decreased.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉The above schematic diagram can be clearly stated: With the heat treatment temperature increasing, the change of the lubricant and the alumina insulation layer the and its effects on the properties of the alumina-coated iron-based SMCs material are well explained.〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S030488531832331X-ga1.jpg" width="417" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 April 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 475〈/p〉 〈p〉Author(s): Ch. Gritsenko, A. Omelyanchik, A. Berg, I. Dzhun, N. Chechenin, O. Dikaya, O.A. Tretiakov, V. Rodionova〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We demonstrate how the configuration and magnitude of a magnetic field, applied during magnetron sputtering of a NiFe/IrMn bilayer, influence the magnetic properties of the structure, such as hysteresis loop shape, coercivity, and exchange bias. Furthermore, we illustrate that it is possible to create a stepwise hysteresis loop in the sample’s region with the highest field gradient. The found features can be used for future sensor applications.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): E.A. Zvereva, T.M. Vasilchikova, M.I. Stratan, S.A. Ibragimov, I.S. Glazkova, A.V. Sobolev, A.N. Vasiliev〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉X-band ESR technique has been successfully applied to study 〈em〉S〈/em〉 = 1/2 spin chain compound vanadyl diacetate VO(CH〈sub〉3〈/sub〉COO)〈sub〉2〈/sub〉. Parameter of the intrachain interactions for uniform Heisenberg antiferromagnetic chain amounts to 〈em〉J〈/em〉/〈em〉k〈sub〉B〈/sub〉〈/em〉 = −167 К, while the ratio between the interchain (〈em〉J〈/em〉′ 〈 0.02 К) and intrachain interactions in this compound reaches a remarkably low value 〈em〉k〈/em〉 = 〈em〉J〈/em〉′/〈em〉J〈/em〉 ∼ 10〈sup〉−4〈/sup〉. Our findings are in consistence with spin-singlet quantum ground state.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): S.L. Hu, J. Liu, H.Y. Yu, Z.W. Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Nano-powders with controllable particle size, excellent magnetic properties and thermal stability of barium hexaferrite (BaFe〈sub〉12〈/sub〉O〈sub〉19〈/sub〉) have been synthesized via a co-precipitation/calcination technique. The phase composition, morphology and magnetic/thermal properties of the products were systematically studied. XRD patterns reveal that a long co-precipitation reaction time (5 h) and high calcination temperature (1100 °C) are beneficial for the formation of BaFe〈sub〉12〈/sub〉O〈sub〉19〈/sub〉 phase and decreasing the tendency to agglomeration. SEM micrographs show that the products show a hexagonal flake-like particle shape and the size are well controlled and maintained at single-domain particle size range area (〈460 nm), above which the coercivity will decrease abruptly for the coupling exchange among particles. The products with 〈em〉〈sub〉j〈/sub〉H〈sub〉c〈/sub〉〈/em〉 of 5934 Oe, temperature coefficient of remanence (〈em〉α〈sub〉Br〈/sub〉〈/em〉) of −0.176% K〈sup〉−1〈/sup〉 and temperature coefficient of coercivity (〈em〉β〈sub〉jHc〈/sub〉〈/em〉) of 0.0427% K〈sup〉−1〈/sup〉 were obtained when co-precipitated for 5 h and calcined at 900 °C for 2 h. A high saturation magnetization of 66.9 emu/g was obtained when co-precipitated for 5 h and calcined at 1100 °C for 2 h, approaching the theoretical saturation magnetization (72 emu/g).〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 472〈/p〉 〈p〉Author(s): Prabhanjan D. Kulkarni, P.V. Sreevidya, Jakeer Khan, P. Predeep, Harish C. Barshilia, P. Chowdhury〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The M-H hysteresis curves of field cooled CoFe/FeMn bilayers and CoFe/FeMn/CoFe trilayers were studied to understand the exchange bias phenomena in these systems. The measured data revealed that the values of the exchange bias corresponding to a bottom CoFe layer reduced by about 23.5% with an addition of another CoFe layer at the top of bilayer stack. It was also observed that, while this reduction in exchange bias of a bottom CoFe layer (calculated in %) depends on thicknesses of a top CoFe layer and an antiferromagnetic FeMn layer, it is independent of the thickness of bottom CoFe layer. As the strength of exchange bias depends on the presence of pinned uncompensated moments in an antiferromagnetic layer, our observations indicate that the FeMn layer consists comparatively lower amount of pinned uncompensated moments in trilayers. This reduction in pinned uncompensated moments of FeMn layer in trilayers is then co-related with the domain wall suppression in the FeMn layer in CoFe/FeMn/CoFe trilayers.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): Sahar Oroujizad, Mohammad Almasi-Kashi, Sima Alikhanzadeh-Arani〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉CoNi binary alloy nanoparticles were prepared by using a polyol method. The effect of the Cu additive (acting as the third element) on structural and magnetic properties of the CoNi〈sub〉50−x〈/sub〉Cu〈sub〉x〈/sub〉 (10 ≤ x ≤ 40) alloy was then studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), magnetometry and first-order reversal curve (FORC) analyses. It was found that a combination of Co-Ni alloy and Cu phases is formed when increasing the Cu content by x = 10 and 20. However, for x = 30 and 40, the resulting compound is obtained in the form of a single-phase ternary alloy. Increasing the Cu content increases the separation between soft and hard phases in the FORC diagram, leading to two distinct magnetic phases in CoNi〈sub〉10〈/sub〉Cu〈sub〉40〈/sub〉. The FORC data showed that the magnetic interaction between particles was reduced when increasing the Cu content. The reversible and irreversible components of the compounds were also estimated. The FESEM images showed the formation of ordered spherical CoNi alloy grains with a diameter of about 400 nm, comprising tight nanoparticles with sizes below 100 nm. Moreover, in the presence of the element Cu, a variation in the nanoparticle size and morphology was seen clearly.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 22 September 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials〈/p〉 〈p〉Author(s): Saadia Rasheed, Rafaqat Ali Khan, Faheem Shah, Bushra Ismail, Jan Nisar, Syed Mujtaba Shah, Abdur Rahim, Abdur Rahman Khan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A series of Li-Cd doped cobalt ferrites CoLi〈sub〉x〈/sub〉Cd〈sub〉x〈/sub〉Fe〈sub〉2-2x〈/sub〉O〈sub〉4〈/sub〉(x= 0.05, 0.1, 0.15, 0.2, 0.25) has been synthesized by hydrothermal method in the presence of cetyltrimethylammonium bromide (CTAB) as capping agent. XRD data has confirmed the formation of single crystalline cubic phase with average crystallite size of synthesized samples between 24-28nm. For all the samples the resistivity was found to increase with increase in dopants concentration with highest value of 7.3〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si4.gif" overflow="scroll"〉〈mo〉×〈/mo〉〈/math〉 10〈sup〉7〈/sup〉ohm.cm at Li-Cd content x= 0.1. Dielectric constant values of all the samples follow the typical Maxwell-Wagner type dispersion due to interfacial polarization and were observed to decrease with increase in frequency, which is a typical phenomenon in ferrites. The coercivity (〈em〉H〈sub〉c〈/sub〉〈/em〉), saturation magnetization (〈em〉M〈sub〉s〈/sub〉〈/em〉) and remanent magnetization (〈em〉M〈sub〉r〈/sub〉〈/em〉) of all the samples increase with dopant content, with maximum values of 936 Oe, 54 emug〈sup〉-1〈/sup〉 and 30 emug〈sup〉-1〈/sup〉 respectively at x=0.1. The obtained data with improved coercivity, saturation magnetization and remanent magnetization make Li-Cd doped cobalt ferrites as suitable materials for utilization in transformer cores and transmission lines.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 5 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials〈/p〉 〈p〉Author(s): Diana L. Torres, Paulo A. Suzuki, Daniel R. Cornejo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Novel heterostructures of Ni〈sub〉x〈/sub〉Ti〈sub〉1-x〈/sub〉/Ni and Ni〈sub〉x〈/sub〉Ti〈sub〉1-x〈/sub〉/Co, with 0.48 〈 x 〈 0.51 grown on Si (100) substrates using DC magnetron co-sputtering were investigated by SQUID magnetometry in the temperature range 10-400 K. The magnetic measurements showed an anomalous enhancement of the total magnetic moment and changes in the coercivity with temperature. These results are attributed to interfacial strain during the structural phase transition of NiTi and evidence the magnetoelastic coupling on these heterostructures. The anomalous enhancement in the magnetic moment is explained in terms on the additional anisotropy in the ferromagnetic layer induced by the interfacial stress. Such heterostructures attached to silicon can be thought of as potential devices for controlling magnetic properties by temperature.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 29 September 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials〈/p〉 〈p〉Author(s): Olaf Kosch, Hendrik Paysen, James Wells, Felix Ptach, Jochen Franke, Lucas Wöckel, Silvio Dutz, Frank Wiekhorst〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉To aid the optimization and development of Magnetic particle imaging (MPI), an accurate and translatable apparatus and a methodology for the characterisation of imaging quality are required. This requires magnetic nanoparticles (MNP) as imaging tracer for MPI measurements in a long-term stable, defined state, since MNP in liquid suspension might tend to change their magnetic properties over time, e.g. as a result of particle aggregation, sedimentation, or disintegration. To this end, we have developed solid phantoms containing freeze-dried perimag in mannitol for the comparison of resolution capabilities between different MPI scanners. Freeze drying of MNP was determined to be the optimal immobilisation method for maintaining the dynamic magnetic properties of MNP as compared with polymer or starch techniques.〈/p〉 〈p〉Freeze-drying preserves the particle distribution, preventing the particles from aggregation or precipitation. Two different types of phantoms were developed, one (cross shaped) to seek for artefacts within reconstructed images, and one (coil shaped) to test the resolution limit. The resolution limit is determined from the coil phantom by measuring the smallest resolvable gap between the two adjacent tracer regions. Our resolution phantom contained a 2 mm wide channel filled with tracer. By using this phantom, the imaging performance of the preclinical MPI system and a prototype gradiometric separate receive coil installed within the same MPI scanner was determined. We found 2.1-2.2 mm resolution limit using the conventional set-up and 0.5-0.6 mm for the separate receive coil resulting in an improvement by factor four. Additionally, the resolution dependency on the channel wide was tested by a second resolution phantom contained a 1 mm wide channel. The long-term stability of the phantoms will be continuously monitored and improved.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 472〈/p〉 〈p〉Author(s): Andrzej Pawlak, Rıza Erdem, Gül Gülpınar〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The expressions for dynamic (complex) dipolar and quadrupolar susceptibilities are obtained within the framework of the linear theory of irreversible thermodynamics in the Blume-Emery-Griffiths model. Frequency, temperature as well as crystal field dependences of the dispersion relations and absorption factors are investigated for two different phase diagram topologies which take place for K/J = 3 and K/J = 5.0. Their behaviors near the second- and first-order transition points as well as multi-critical points such as tricritical, triple and critical endpoint are presented.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): S. Morteza Mousavi, A. Ali Rabienataj Darzi, Omid ali Akbari, Davood Toghraie, Ali Marzban〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this paper, the influence of a non-uniform magnetic field on biomagnetic fluid flow in a duct with a constriction is investigated numerically. The magnetic field is generated by a wire carrying electric current located outside the duct. The biomagnetic fluid dynamics model, which is based on the ferrohydrodynamics and magnetohydrodynamics, is used to study the fluid flow, and a computational grid properly covering the magnetic field is used for the simulation. In this investigation, the influence of magnetic field on biomagnetic fluid flow in various percentages of the duct constriction, and the effect of the magnetic field on the biomagnetic fluid flow in various strengths of magnetic force are studied. The magnetic field is spatially varying, and the magnetic field strength decreases by increasing the distance from the wire carrying electric current which is the magnetic source. The results show that, the influence of the magnetic field on biomagnetic fluid flow is considerable near the magnetic source. Applying the magnetic field with enough strength causes the recirculation areas downstream of constriction to become smaller. In addition, applying the magnetic field has significant effects on the wall shear stress, so that it can decrease the shear stress on the wall away from the magnetic source.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): G. Frajer, O. Isnard, H. Chazal, G. Delette〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉This paper investigates the effect of the cobalt addition on the magneto-crystalline anisotropy parameter of some polycrystalline ferrites. Magnetization curves have been experimentally determined at different temperatures on Ni〈sub〉1−x〈/sub〉Zn〈sub〉x〈/sub〉Fe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 sintered samples with or without cobalt addition. In each case, a law of approach to saturation has been fitted to the measured data in order to extract the anisotropy parameter 〈em〉K〈sub〉1〈/sub〉〈/em〉 representative for the polycrystalline material.〈/p〉 〈p〉Besides, measurement of the complex susceptibility and power core-loss up to 5 MHz has been performed. This approach allows a discussion on the role of cobalt addition on the power core-loss mitigation. It has been found that the substitution with 0.02 mol. of Co leads to a small decrease in the 〈em〉K〈sub〉1〈/sub〉〈/em〉 values. This evolution is consistent with the rise in the rotational permeability. However, the change in 〈em〉K〈sub〉1〈/sub〉〈/em〉 cannot account for the core-loss reduction with Co. Rather, it is confirmed that Co hinders the domain wall displacement and subsequent dissipation up to an induction level that depends on the grain size.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): Lixia Zhang, Qinlu Zhang, Min Gao, Zhiyi Luo, Ying Zhang, Xiaoxia Li, Kai Hua, Chao Zhang, Wenting Lai, Yali Cui〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈h6〉Objective〈/h6〉 〈p〉To investigate the consistency between GoldMag® immunochromatography and immune scatter turbidimetry in hs-CRP detection.〈/p〉 〈/div〉 〈div〉 〈h6〉Methods〈/h6〉 〈p〉The data of hs-CRP were collected from 78 hospitalized patients, and these patients were divided into fingertip blood group and the venous blood group according to the different blood collection methods. The whole blood and plasma level of hs-CRP was detected by GoldMag® immunochromatography and immune scatter turbidimetry. Correlation analysis was carried out to compare the data of hs-CRP obtained by different approaches.〈/p〉 〈/div〉 〈div〉 〈h6〉Results〈/h6〉 〈p〉In both fingertip blood group and venous blood group, the concentration of hs-CRP determined by GoldMag® immunochromatography were positively correlated with those found with immune scatter turbidimetry. There was no significant difference in the level of hs-CRP provided by these two different approaches. (P 〉 0.05).〈/p〉 〈/div〉 〈div〉 〈h6〉Conclusion〈/h6〉 〈p〉GoldMag® immunochromatographic assay has good uniformity with immune scatter turbidimetry Scatter Turbidimetric Method for hs-CRP detection. Based on the double antibody sandwich method, antibody labeled GoldMag nanoparticles capture hs-CRP from whole blood or plasma and aggregate in test line of test strip. The magnetic intensity of agglomerated GoldMag® nanoparticles collected is measured by magnetic quantitative immunoassay analyzer. The concentration of hs-CRP can be obtained according to the standard curve between concentration and magnetic intensity. GoldMag® immunochromatography is served as an easy operation, high accuracy and stable method.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 29 June 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials〈/p〉 〈p〉Author(s): N.Yu. Pankratov, V.I. Mitsiuk, V.M. Ryzhkovskii, S.A. Nikitin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The equiatomic intermetallic alloy MnZnSb with a tetragonal Cu〈sub〉2〈/sub〉Sb-type crystal structure (space group P4/nmm) was melted in the resistance furnace in the evacuated quartz ampoule. The adiabatic temperature change 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si7.gif" overflow="scroll"〉〈mrow〉〈mo stretchy="false"〉(〈/mo〉〈mi mathvariant="normal"〉Δ〈/mi〉〈msub〉〈mrow〉〈mi〉T〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="normal"〉ad〈/mi〉〈/mrow〉〈/msub〉〈mo stretchy="false"〉)〈/mo〉〈/mrow〉〈/math〉 and the isothermal variation of the magnetic entropy (〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si8.gif" overflow="scroll"〉〈mrow〉〈mi mathvariant="normal"〉Δ〈/mi〉〈msub〉〈mrow〉〈mi〉S〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="normal"〉M〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉) of the MnZnSb compound near to the magnetic phase transition were studied. The 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈mi mathvariant="normal"〉Δ〈/mi〉〈msub〉〈mrow〉〈mi〉T〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="normal"〉ad〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 in a magnetic field up to 1.25 T was studied by the direct method. It was found that temperature dependencies of both 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈mi mathvariant="normal"〉Δ〈/mi〉〈msub〉〈mrow〉〈mi〉T〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="normal"〉ad〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 and 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si8.gif" overflow="scroll"〉〈mrow〉〈mi mathvariant="normal"〉Δ〈/mi〉〈msub〉〈mrow〉〈mi〉S〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="normal"〉M〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 show a sharp peak near room temperature with a maximum at Curie temperature 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si4.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mi〉T〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="normal"〉C〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 = 317 K. It was shown that there is no temperature hysteresis of the 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈mi mathvariant="normal"〉Δ〈/mi〉〈msub〉〈mrow〉〈mi〉T〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="normal"〉ad〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 in MnZnSb, and the maximum of 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈mi mathvariant="normal"〉Δ〈/mi〉〈msub〉〈mrow〉〈mi〉T〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="normal"〉ad〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 when the compound is heated or cooled is detected at the same temperature. The estimated value of 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈mi mathvariant="normal"〉Δ〈/mi〉〈msub〉〈mrow〉〈mi〉T〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="normal"〉ad〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 in a field of 14 T is 4.5 K. It was shown that near the Curie temperature, the field dependence of the maximum of magnetic entropy change is adequately described by the thermodynamic Landau theory for magnetic second-order phase transitions.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): Jian-feng Zhou, Song Zhang, Feng Tian, Chun-lei Shao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Magnetic particles (MPs) have good response to external magnetic field. To investigate the motion regularity of MPs in a mcirochannel flow governed by alternating gradient magnetic field, a 3D numerical simulation method is established based on the lattice Boltzmann method (LBM) and the immersed boundary method (IBM). The motions of both a single MP and a short chain of MPs are investigated and each is found to be a superposition of transverse oscillation and longitudinal translation. By performing a simple filtering processing for the original trajectory of MP, it is revealed that the oscillation of MPs affected by alternating gradient magnetic field can be characterized as the simple harmonic vibration. The oscillation frequency of MPs is basically in accordance with the alternating frequency of the gradient magnetic field in the range from 400 to 800 Hz. The larger magnetic field gradient results in the larger amplitude of oscillation. The wavelength of the trajectory is increased due to the increasing inlet velocity of carrier fluid. For the MP chain, both the period and amplitude of oscillation will decrease with the increase of alternating frequency of magnetic field. The turbulence intensity distribution indicates that the turbulence of microchannel flow can be enhanced by the oscillation of MPs thus enhance the mass or heat transfer in the carrier fluid.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): Zuzana Bednarikova, Jozef Marek, Erna Demjen, Silvio Dutz, Maria-Magdalena Mocanu, Josephine W. Wu, Steven S.-S. Wang, Zuzana Gazova〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉More than 50 diseases are associated with a conversion of proteins or peptides from their soluble functional states to highly organized fibrillar aggregates called amyloid fibrils. Due to the specific physico-chemical properties, specifically designed iron oxide nanoparticles may be an effective strategy for inhibiting the amyloid fibrillization of proteins. The inhibitory effect of three types of iron oxide nanoparticles coated with differently modified dextran on lysozyme fibrils formation was studied by Thioflavin T assay and atomic force microscopy. The size and zeta potential of studied nanoparticles were determined by dynamic light scattering. It had been found that nanoparticles are able to inhibit formation of lysozyme amyloid aggregates in concentration-dependent manner. Our results suggest that size of nanoparticles influenced the extent of their inhibitory properties. Moreover, the most effective nanoparticles were not toxic after 48 h incubation with neuroblastoma SH-SY5Y cell line at concentration close to IC〈sub〉50〈/sub〉 values.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): X.W. Dong, R.F. Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The chirality-dependent propagations of transverse domain walls (DWs) in two types of Y-shaped nanostrips under small driving fields were investigated using micromagnetic simulations. They both exhibit the well DW chirality selection behaviors and the hugely reduced DW transmission fields owing to the specific magnetic charge distributions on both the junction and corners. The DW transmission field even can be as small as 2 Oe. Additionally, the DW chirality can be controlled by applying an out-of-plane field, leading to the use of the Y-shaped nanostrips as logic devices, such as selector, rectifier and amplifier.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): Caio C. Quini, André G. Próspero, Bethany R. Kondiles, Lesley Chaboub, Matthew K. Hogan, Oswaldo Baffa, Andris F. Bakuzis, Philip J. Horner, José R.A. Miranda〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Several applications of nanoparticles rely on the internalization and accumulation of nanocarriers in specific cell compartments and tissues. However, the methods currently employed for characterizing such processes, although well described, are time consuming and do not provide 〈em〉in vivo〈/em〉 information, which is a crucial barrier towards translational applications. Here, we hypothesize that the AC Biosusceptometry technique can be employed to assess cell internalization of magnetic nanoparticles, with possible applications in screening assays to track specific biomarkers and cell types. We tested a simpler and easier alternative to study cell internalization and tissue accumulation after perfusion. We utilized citrate coated, manganese ferrite nanoparticles and evaluated the internalization process in mouse macrophages cells (J774.A1) and in an embryonic neural stem cell culture (E14.5) after differentiation in astrocytes and neurons, to assess internalization specificity. Respecting the particles toxicity limits, we tested different concentration of particles, in different incubation times. Sequentially, we imaged the cell cultures to confirm internalization and nanoparticles localization, labeling nucleus and cell body to assure that the particles were inside the cells. Our results showed a linear behavior on internalization for different doses and an optimum incubation time of 2 h.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): E. Petrova, D. Kotsikau, V. Pankov, A. Fahmi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Structural characteristics and magnetic properties of Mg〈em〉〈sub〉x〈/sub〉〈/em〉Zn〈sub〉1–〈/sub〉〈em〉〈sub〉x〈/sub〉〈/em〉Fe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 (〈em〉x〈/em〉 = 0.25; 0.5; 0.7) nanomaterials prepared by autocombustion, co-precipitation and spray pyrolysis methods were studied. Different characterization techniques are used to study the structural formation of the generated nanoparticles, namely X-ray diffraction (XRD), scanning (SEM) and transmission electron microscopy (TEM), infrared spectroscopy (FT-IR) and vibrating sample magnetometery (VSM). In case of citrate autocombustion and co-precipitation methods, the magnetization goes through a maximum at Mg〈sub〉0.5〈/sub〉Zn〈sub〉0.5〈/sub〉Fe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 composition, while the dependence on the composition is subtle for spray pyrolysis. An increase in temperature and duration of heat treatment during the synthesis process leads to a particle size growth and to a cation redistribution between spinel sub-lattices. These resulted in a significant increase in the specific magnetization of the particles generated by citrate autocombustion method. The nanoparticles synthesized by co-precipitation method exhibit superparamagnetic behavior with no coercivity at room temperature. Nonetheless, the materials prepared by spray pyrolysis and citrate autocombustion methods are found to possess small coercivity of 30–80 Oe. The highest specific magnetization at room temperature is referring to Mg〈sub〉0.5〈/sub〉Zn〈sub〉0.5〈/sub〉Fe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 nanoparticles obtained by citrate autocombustion method (30 emu/g). The revealed correlations can be used to synthesize spinel ferrite nanoparticles with well-defined collective properties for a wide spectrum of applications.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 472〈/p〉 〈p〉Author(s): P. Kuświk, M. Matczak, M. Kowacz, F. Lisiecki, F. Stobiecki〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The determination of the interfacial Dzyaloshinskii-Moriya interaction for perpendicularly magnetized thin layered films is not trivial and therefore needs some experimental efforts to determine its sign and magnitude, especially in exchange biased systems. Here, we modified a method proposed by D.-S. Han et al. [Nano Lett. 16, (2016) 4438], which opens a way to investigate this interaction using conventional PMOKE magnetometry in exchange biased systems as well. Using our approach we demonstrated that the Au/Co/NiO layered system has a strong negative Dzyaloshinskii-Moriya interaction which is independent of the direction of perpendicular exchange bias coupling.〈/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-S0304885318312617-ga1.jpg" width="248" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 472〈/p〉 〈p〉Author(s): Shu Guo, Tai Kong, F. Alex Cevallos, Karoline Stolze, R.J. Cava〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Crystals of the KBa〈em〉R〈/em〉(BO〈sub〉3〈/sub〉)〈sub〉2〈/sub〉 (〈em〉R〈/em〉 = Y, Gd, Tb, Dy, Ho, Tm, Yb and Lu) rare earth borates were grown by spontaneous nucleation from a KF-B〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 flux. The crystals obtained were typically well-developed hexagonal plates about 1 mm in large dimension. The crystals were used to study the anisotropic temperature and field dependent magnetization of the materials, which are based on ideal triangular planes of magnetic rare earths. All structures were refined in space group R〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈mover〉〈mn〉3〈/mn〉〈mo〉-〈/mo〉〈/mover〉〈/mrow〉〈/math〉m by single-crystal X-ray diffraction, and in addition to the equilateral triangular rare earth plane lattice, displayed K/Ba site occupancy disorder. All magnetic compounds reveal dominantly antiferromagnetic spin interactions with no magnetic ordering above 1.8 K. With the exception of KBaGd(BO〈sub〉3〈/sub〉)〈sub〉2〈/sub〉, magnetic anisotropy was observed for other five magnetic members of the family. The results suggest that KBa〈em〉R〈/em〉(BO〈sub〉3〈/sub〉)〈sub〉2〈/sub〉 crystals may be of further interest for investigating the magnetic properties of rare earth ions on a triangular lattice.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): X.T. Li, M. Yue, S.X. Zhou, C.J. Kuang, G.Q. Zhang, B.S. Dong, H. Zeng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Hydrogen treatment technology is developed to recycle the waste Nd-Fe-B sintered magnets in the way of short route, low cost, and high efficiency. In present study, effect of hydrogen pressure on hydrogen decrepitation (HD) process of sintered Nd-Fe-B strip casting flakes (SC) and waste sintered magnets (SM) was systematically studied. Both SC and SM show the approximate HD process, which accelerates with increasing pressure. The surface activation process accelerates with increasing pressure, and almost disappears when the initial hydrogen pressure reaches to 6 MPa. The hydrogen content of SM is lower than SC, and increases with increasing pressure. For the SM, blasting power of HD process decreases with the increase of the initial hydrogen pressure. It provides beneficial reference for recycling waste Nd-Fe-B sintered magnets.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): Grant V.M. Williams, John Kennedy, Peter P. Murmu, Sergey Rubanov, Shen V. Chong〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Structural and magnetic measurements were performed on SiO〈sub〉2〈/sub〉 films containing near-surface Ni〈sub〉1−〈/sub〉〈em〉〈sub〉x〈/sub〉〈/em〉Fe〈em〉〈sub〉x〈/sub〉〈/em〉 superparamagnetic nanoparticles made by low energy ion implantation into SiO〈sub〉2〈/sub〉 with the same Ni fluences of 2 × 10〈sup〉16〈/sup〉 at./cm〈sup〉2〈/sup〉 and two different Fe fluences so that 〈em〉x〈/em〉 = 0.47 and 〈em〉x〈/em〉 = 0.20. The 〈em〉x〈/em〉 = 0.47 films had larger nanoparticles, a higher fraction of ordered moments in the nanoparticle cores, and thinner spin-disordered shells. The nanoparticle core spin-stiffnesses were slightly higher for 〈em〉x〈/em〉 = 0.20 and smaller than that expected for bulk Ni〈sub〉1−〈/sub〉〈em〉〈sub〉x〈/sub〉〈/em〉Fe〈em〉〈sub〉x〈/sub〉〈/em〉 for both Fe concentrations. There was no evidence for magnetic dipole interactions between the nanoparticles that have been reported in compressed superparamagnetic ferromagnetic nanoparticles. d〈em〉M〈/em〉/d〈em〉H〈/em〉 was estimated and found to be highest for 〈em〉x〈/em〉 = 0.47 where it reached 15 at 300 K and 56 at 100 K. The measured d〈em〉M〈/em〉/d〈em〉H〈/em〉 is consistent with that expected from a derivative of the Langevin function with negligible demagnetization where larger nanoparticles are expected to have a higher d〈em〉M〈/em〉/d〈em〉H〈/em〉.〈/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-S0304885318324260-ga1.jpg" width="342" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): Luděk Kraus, Jaromír Kopeček〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The influence of surface magnetic anisotropy on ferromagnetic resonance (FMR) in submicron wires is investigated both theoretically and experimentally. An analytical formula for resonance fields of radial spin waves in a long axially magnetized circular cylinder is obtained. Three types of surface anisotropy with the easy direction along one of the cylindrical coordinates are considered. For sufficiently strong surface anisotropy with hard direction parallel to the cylinder axis the surface spin wave mode is observed. The theoretical results are verified by FMR measurements at six microwave frequencies from 9 to 69 GHz on glass-covered amorphous FeCrSiB wires with diameters from 541 to 1032 nm. From the bulk spin wave resonances the exchange stiffness constant about 6.5 10〈sup〉−7〈/sup〉 erg/cm is obtained. The frequency dependence of the surface mode resonance field indicates that a perpendicular surface anisotropy with anisotropy constant 〈em〉K〈sub〉s〈/sub〉〈/em〉 = 6.2 erg/cm〈sup〉2〈/sup〉 is present at the metal/glass interface.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 11 September 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials〈/p〉 〈p〉Author(s): Z. Jalali-Mola, S.A. Jafari〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In systems with substantial spin fluctuations, dressing the polarization function by ladder diagram of Stoner (spin-flip) excitations can drastically modify the electromagnetic response. As a case study we provide the detailed analysis of the corrections to the non-local optical conductivity of both doped and undoped graphene. While the resummation of ladder diagram of Stoner excitations does not affect the TE mode in doped graphene, it allows for a new 〈em〉undamped〈/em〉 TM mode in undoped graphene. This is the sole effect of corrections arising from ladder diagrams and is dominated by Stoner excitations along the ladder rung which goes away by turning off the source of spin-flip interactions. In the case of doped graphene, the inclusion of spin-flip particle-hole fluctuations reduces the energy of plasmon mode.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 April 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 476〈/p〉 〈p〉Author(s): K. Elayakumar, A. Dinesh, A. Manikandan, Murugesan Palanivelu, G. Kavitha, S. Prakash, R. Thilak Kumar, Saravana Kumar Jaganathan, A. Baykal〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this present study, we made an attempt for the different concentration of rare earth element (REE) Cerium (Ce〈sup〉3+〈/sup〉) doped cobalt ferrite (CoFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉) nanoparticles (NPs) were prepared by the simple sol-gel combustion technique. Cerium was successfully substituted into the spinel lattice without any distortion. It was analyzed the effect of Ce〈sup〉3+〈/sup〉 ions doping on structural, morphological, magnetic properties and antibacterial activities using the various instrument techniques. Powder XRD and SEM along with EDX studies confirmed the pure phase formation Ce〈sup〉3+〈/sup〉 doped CoFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 NPs and spherical shaped agglomerated nanoparticles morphology without any other impurity. The well resolved broad peaks in the XRD pattern clearly indicated the nanosized, single phased, cubic spinal nature of these samples. There was a substantial decrease in the crystallite size on doping with Ce〈sup〉3+〈/sup〉. A more in-depth morphological study was facilitated using the TEM and SAED analysis. TEM investigation revealed random shaped, sharp edged nanoparticles with a normally facetted morphology. The presence of distinctive diffractions spots on the SAED pattern indicated the formation of nanoparticles that are highly crystalline in nature. The magnetic response of the Ce〈sup〉3+〈/sup〉 doped CoFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 NPs was recorded at room temperature (RT) using the VSM technique. The magnetic properties have been seen to be altered by the addition of Ce〈sup〉3+〈/sup〉 in the CoFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 matrix. The decrease in the saturation magnetization (M〈sub〉s〈/sub〉, emu/g) with the increase in Ce〈sup〉3+〈/sup〉 content rendered the synthesized sample applicable in field of antenna construction. This change will be also suitable for reducing the size of the antenna. The antibacterial activity of Ce〈sup〉3+〈/sup〉 doped CoFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 nanoparticles was found to be enhanced with increase in Ce〈sup〉3+〈/sup〉 doping level as it cause a reduction in the grain size.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 11 July 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials〈/p〉 〈p〉Author(s): G. Kontrym-Sznajd, S.B. Dugdale〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We show how to calculate isotropic Compton profiles from sets of profiles along so-called “special directions” in the Brillouin zone computed from density-functional theory calculations, with reference to a recent paper by Bhatt et al. We present the correct formula and demonstrate the power of special directions, highlighting the importance of carefully choosing directions and using the correct weights in obtaining accurate isotropic profiles.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): R. Rajesh kumar, Rishav Raj, A. Venimadhav〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We report on the tunable band engineering in α-(Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉)〈sub〉1−X〈/sub〉(Cr〈sub〉2〈/sub〉O〈sub〉3〈/sub〉)〈sub〉X〈/sub〉 nanoparticles. Nanoparticles were prepared by the sol-gel method and stabilised in the hexagonal crystal structure with R-3C space group. At room temperature band-gap studies have shown the narrowing of the band gap from 2.1 eV to 1.6 eV with Cr addition. Compared to antiferromagnetic α-Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 nanoparticles, doping of Cr〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 increases the magnetic hysteresis significantly. Impedance spectroscopic studies have revealed Maxwell-Wagner dielectric relaxation near room temperature. Our results improve the understanding of the structural, optical, dielectric and magnetic properties of Cr-doped α-Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 nanoparticles and illustrates that these nanoparticles have potential candidate in spintronic, optoelectronic, solar cell and photocatalysis applications.〈/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-S0304885318328749-ga1.jpg" width="346" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): Byung-Kwan Lim, Elyse C. Tighe, Seong Deok Kong〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉With the continuous technological advancements being made in the medical field every day, the ability to improve drug delivery uptake in cardiac research is a prominent topic of discussion. Nanoparticles provide the opportunity to improve the efficiency of drug therapy while minimizing chemotherapy side effects through controllably releasing the encapsulated drug at the target site. Mono-disperse Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 nanoparticles/polystyrene composite nanospheres with a large volume fraction of trapped magnetite and fluorophores were used in an 〈em〉in vivo〈/em〉 experiment. In this study, magnetic nanoparticles were successfully delivered into the heart by utilizing magnetic targeting. Magnetic targeting allowed the mono-disperse Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 nanospheres to be dramatically localized in the heart myocardium. This increased the quantity of delivery to the cardiac myocytes in comparison to magnetic nanospheres without magnetic targeting.〈/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-S0304885318319747-ga1.jpg" width="282" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): Maryam Youhannayee, Saeideh Nakhaei-Rad, Fereshteh Haghighi, Karsten Klauke, Christoph Janiak, Mohammad Reza Ahmadian, Robert Rabenalt, Peter Albers, Mathias Getzlaff〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Among nanoparticles, magnetic nanoparticles are the most appealing candidate for diagnosis and cancer therapy. The researchers are tempting to improve the particles properties, including the size, shape, coating, and magnetic behavior or heating characteristics. Core shell type of magnetic nanoparticle is an important property that modulates their internalization 〈em〉via〈/em〉 normal and cancer cells. In this study, magnetite nanoparticles (MNP) covered by N-(2-aminoethyl)-3-aminopropyltriethoxysilane (aminosilane – APTES) were synthesized by co-precipitation of aqueous solution of ferric chloride and ferrous sulfate iron salts with ammonium hydroxide as a base and functionalized by APTES to increase the viability and affinity of the particles to the cancer cells. The structural and morphological properties of these particles were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transformed infrared spectroscopy (FTIR). 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl tetrazolium bromide (MTT assay) was carried out, to check the viability of the cells treatment with MNP and APTES-MNP. To study the cellular uptake 〈em〉in vitro〈/em〉, two prostate cell lines were investigated: PC3 as a cancerous cell line and BPH1 as a benign epithelial cell line (normal cells). Both cell lines were incubated for 24 h with different concentrations of MNP and APTES-MNP (100 and 500 μg/ml and one untreated sample as control). TEM and flow cytometry (FC) analyses were subsequently carried out to monitor the cellular uptake of MNP and APTES-MNP. FC data revealed an increase in cell granularity following the treatment with high concentration of the particles. Data showed that PC3 cancer cells take up more APTES-MNP with respect to control cells than BPH1 benign cells and in contrast BPH1 cell uptake MNP correlated to control cells more efficient than PC3 cells. The results from FC and TEM analyses demonstrate increasing of affinity of particles to cancer cell line (PC3). In this project we investigated the effect of surface functionalization of NP to affinity of the MNP and APTES-MNP on PC3 cells as a malignancy prostate cell and BPH1 benign cells as a normal cells. This approach may help to optimize the efficiency of hyperthermia for prostate cancer through internalization of particles to the cells or attaching to the membrane.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): Hongchao Cui, Decai Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Conventional ferrofluids are not satisfactory in special fields, especially in corrosive and extreme temperature conditions. In this study, perfluoropolyether based ferrofluid with outstanding performance was synthesized by high energy ball milling. The results of XRD, TEM and particle size analyzer show that the modified Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 is well crystallized, globular shaped and monodisperse. Magnetic particles in a narrow size distribution ranging from 8 nm to 15 nm and the average is approximately 10 nm. Characteristic peaks in FT-IR and XPS spectrum confirm that Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 MNPs are successfully decorated by perfluoropolyether carboxylic acid surfactant. Perfluoropolyether based ferrofluid exhibits superparamagnetism, and magnetization is 22.83 emu/g at 10 kOe. Surface tension of perfluoropolyether based ferrofluid is 25.18 mN/m at 25 °C; Viscosity decreases with temperature increasing, which can be fitted as 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈mtext〉η〈/mtext〉〈mtext〉=〈/mtext〉〈msup〉〈mrow〉〈mtext〉e〈/mtext〉〈/mrow〉〈mrow〉〈mtext〉a+bT+c〈/mtext〉〈msup〉〈mrow〉〈mtext〉T〈/mtext〉〈/mrow〉〈mtext〉2〈/mtext〉〈/msup〉〈/mrow〉〈/msup〉〈/mrow〉〈/math〉. In heating progress from −20 °C to 25 °C, perfluoropolyether based ferrofluid is a non-Newtonian fluid, while from 25 °C to 100 °C, it is a Newtonian fluid with almost constant viscosity. Viscosity of perfluoropolyether based ferrofluid increases to 1825.7 mPa·s at −20 °C and is still flowing at −40 °C. Yield point occurs when deformation reaches to 10%, and increases along with electromagnetic field in magnetic rheological behavior.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 April 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 475〈/p〉 〈p〉Author(s): S. Chaudhary, P. Srivastava, S.D. Kaushik, V. Siruguri, S. Patnaik〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We study magnetocapacitance (MC) effect and magnetoelectric (ME) coupling in spin-flop driven antiferromagnet Co〈sub〉4〈/sub〉Ta〈sub〉2〈/sub〉O〈sub〉9〈/sub〉. Powder neutron diffraction data reveal that the magnetic structure corresponds to a non-collinear arrangement along with a non-centrosymmetric crystal structure below Néel Temperature. Electric polarization is achieved below Néel temperature only when the sample is cooled in the presence of external magnetic field. The magnetocapacitance data at high magnetic fields are analyzed by phenomenological Ginzburg-landau theory of ferro-electromagnets and it is found that change in dielectric constant is proportional to the square of magnetization. The saturation polarization and magnetoelectric coupling are estimated to be 52 µC/m〈sup〉2〈/sup〉 and γ = 1.4 × 10〈sup〉−3〈/sup〉 (emu/g)〈sup〉−2〈/sup〉 respectively at 6 Tesla. Strong magnetoelectric coupling and ferroelectric phase in the anti-ferromagnetic Co〈sub〉4〈/sub〉Ta〈sub〉2〈/sub〉O〈sub〉9〈/sub〉 are correlated to magnetic structure as derived from neutron diffraction data.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): N.B. Melnikov, G.V. Paradezhenko, B.I. Reser〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We study magnetic short-range order in Fe and Ni above the Curie temperature using the nonlocal dynamic spin-fluctuation theory with self-consistent calculation of the self-energy. We calculate the spatial correlation function of Fe and Ni at nearest neighbours, next-nearest neighbours, etc., in a wide range of temperatures. Our results are in agreement with neutron scattering experiments but give a larger short-range order compared to classical spin models. We show that the spatial spin correlator decreases ten times at distances of about 6 Å in Fe and 8 Å in Ni at 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si14.gif" overflow="scroll"〉〈mrow〉〈mi〉T〈/mi〉〈mo〉/〈/mo〉〈msub〉〈mrow〉〈mi〉T〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="normal"〉C〈/mi〉〈/mrow〉〈/msub〉〈mo〉=〈/mo〉〈mn〉1.1〈/mn〉〈/mrow〉〈/math〉 and short-range order remains well above the Curie point.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 472〈/p〉 〈p〉Author(s): Yunchen Wu, Kangkang Meng, Jun Miao, Xiaoguang Xu, Yong Jiang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We report the enhancement of spin-orbit torque (SOT) in Pt/Co/Pt multilayers with inserting Ru layers. From current induced magnetization switching and harmonic measurements, we have found that both the damping-like and field-like effective fields increased with inserting Ru layers. The variation is firstly ascribed to the enhancement of the effective spin accumulation at the Co/Ru interfaces. Meanwhile, the interfacial Rashba effect has also been modulated, which depends on the direction of the internal electric field gradient at the interfaces. Our study provides an alternative way to modulate SOT.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 22 February 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials〈/p〉 〈p〉Author(s): A.A. Amirov, V.V. Rodionov, I.A. Starkov, A.S. Starkov, A.M. Aliev〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the paper there are presented magnetic, magnetoelectric, and magnetocaloric properties of the 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si2.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mi mathvariant="normal"〉Fe〈/mi〉〈/mrow〉〈mrow〉〈mn〉48〈/mn〉〈/mrow〉〈/msub〉〈msub〉〈mrow〉〈mi mathvariant="normal"〉Rh〈/mi〉〈/mrow〉〈mrow〉〈mn〉52〈/mn〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉-PZT bilayer multiferroic composite close to room temperature. The maximum of adiabatic temperature change as well as the large magnetoelectric ordering around the antiferromagnetic-magnetic phase transition temperature of 315 K for a magnetic field change of 0.62 T is demonstrated. The application of a voltage across the bilayer structure shifts the metamagnetic transition by ∼4 K in cooling and by ∼3 K in heating. The magnitude of the magnetoelectric and magnetocaloric effects depends on the strain/stress in the magnetic layer induced by the piezoelectric one as a result of applying electric field. Such a finding can be successfully employed for controlling of the magnetic properties of caloric materials.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 17 September 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials〈/p〉 〈p〉Author(s): Guangbing Han, Ke Wang, Kevin E. Elkins, Zhaoguo Qiu, Richard B. Timmons, Charles R. Savage, Shishou Kang, J. Ping Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Nano-flake SmCo〈sub〉5〈/sub〉 powders with typical flake thickness of 200 nm were prepared by high energy ball milling using Oleic Acid (OA) as a surfactant. In order to remove the surfactant, the as-milled powders were exposed to pulse cold plasma of argon. The effects of the plasma parameters on residual surfactant content and magnetic properties of the resulting powder were investigated. Partial (62.5 at. %) surfactant removal was observed by XPS after treatments of 4 hrs at 150 Watt average power under an argon pressure of 300 mTorr. In addition, the cold plasma cleaning process led to a little bit of increase of oxygen on the surface. Demagnetization measurements revealed a slight decrease of the magnetic performance after plasma treatment. These results indicate that pulse cold plasma is an effective way for surfactant removal without morphological change and magnetic property degradation of the SmCo〈sub〉5〈/sub〉 nano-flakes.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): H. Martínez Sánchez, L.E. Zamora Alfonso, J.S. Trujillo Hernandez, G.A. Pérez Alcázar〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si3.gif" overflow="scroll"〉〈mrow〉〈mi〉τ〈/mi〉〈/mrow〉〈/math〉-MnAlC/FeCo system has potential to be applied as rare earth-free permanent magnet, due to exchange coupled between hard and soft magnetic phases as alternative for the development of high energy product permanent magnets. In this work the hard-magnetic phase Mn〈sub〉53.3〈/sub〉Al〈sub〉45〈/sub〉C〈sub〉1.7〈/sub〉 (〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si7.gif" overflow="scroll"〉〈mrow〉〈mi〉μ〈/mi〉〈/mrow〉〈/math〉〈sub〉0〈/sub〉〈em〉H〈sub〉c〈/sub〉〈/em〉 = 0.37 T of coercive force, 〈em〉M〈sub〉r〈/sub〉〈/em〉 = 23.52 Am〈sup〉2〈/sup〉/kg of remanent magnetization, 〈em〉M〈sub〉s〈/sub〉〈/em〉 = 52.94 Am〈sup〉2〈/sup〉/kg of saturation magnetization and (〈em〉BH〈/em〉)〈sub〉max〈/sub〉 = 3.89 kJ/m〈sup〉3〈/sup〉 of maximum energy product) was mixed with the soft magnetic phase Fe〈sub〉65〈/sub〉Co〈sub〉35〈/sub〉 (〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si7.gif" overflow="scroll"〉〈mrow〉〈mi〉μ〈/mi〉〈/mrow〉〈/math〉〈sub〉0〈/sub〉〈em〉H〈sub〉c〈/sub〉〈/em〉 = 0.007 T and 〈em〉M〈sub〉s〈/sub〉〈/em〉 = 221.33 Am〈sup〉2〈/sup〉/kg) using a solid-state procedure. The magnetic materials were sintered using different ratios of hard and soft magnetic phases: 95:5, 90:10, 85:15 and 80:20; and different sintering temperatures (300, 400, 500 and 600 °C) in order to improve the magnetic properties. The magnetic exchange coupling between MnAlC and FeCo was proved by the hysteresis loop and its corresponding Thamm-Hesse analysis. The best result was obtained for MnAlC/FeCo (95/5 wt%) sintered at 500 °C during 30 min, for which the magnetic properties were 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si7.gif" overflow="scroll"〉〈mrow〉〈mi〉μ〈/mi〉〈/mrow〉〈/math〉〈sub〉0〈/sub〉〈em〉H〈sub〉c〈/sub〉〈/em〉 = 0.277 T, 〈em〉M〈sub〉s〈/sub〉〈/em〉 = 76.43 Am〈sup〉2〈/sup〉/kg and (〈em〉BH〈/em〉)〈sub〉max〈/sub〉 = 5.57 kJ/m〈sup〉3〈/sup〉.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): I. Hrianca〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The thermal dependence of the magnetization of a nanoparticles powder heated from very low temperatures 1–400 K for both cases of cooling in the absence (zfc) and in presence (fc) of a constant magnetic field was studied. In the presence of the magnetic field, the uniaxial anisotropy generates asymmetric double well energy landscapes. The changes with temperature and time of the particles distribution between the two energy minima was examined, and calculations based on particles distribution were developed. At low temperatures, the relaxation time is very long, the transitions between the two energy minima are extremely rare and the particle distribution on the minima does not change. Close to the blocking temperature T〈sub〉B〈/sub〉, the relaxation time becomes much shorter and a significant increase in the transition number takes place, the particle distribution changes and so does the magnetization. Above this temperature, the relaxation time decreases faster, the transitions in both directions come to balance and the particle distribution becomes stable: the magnetization values will correspond to successive thermodynamic equilibrium states, verified by the zfc, fc and td curves superposition. The theoretical results are in good agreement with the experimental data reported by many authors.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): A. Adanlété Adjanoh, R. Belhi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We have used polar Kerr microscopy to study the magnetic domain structure in an ultrathin Au/Co(1 nm)/Au layer with perpendicular magnetic anisotropy. We present our demagnetization method of the sample. In the demagnetized state, we observed a dendritic domain structure. We theoretically calculated the lateral domain size in the demagnetized state by using two different models and we saw that the prefactor 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si7.gif" overflow="scroll"〉〈mrow〉〈mi〉x〈/mi〉〈mo〉=〈/mo〉〈mn〉0.389〈/mn〉〈/mrow〉〈/math〉 corresponds to the domain structure observed. We used polar magneto-optical Kerr effect magnetometry (PMOKE) to study the magnetization reversal and to extract an activation energy 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si8.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mi〉E〈/mi〉〈mi〉a〈/mi〉〈/msub〉〈/mrow〉〈/math〉 in zero field and the width of the distribution of the energy barriers 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si9.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mi〉σ〈/mi〉〈mi〉w〈/mi〉〈/msub〉〈/mrow〉〈/math〉. We correlated the dendritic domain structure observed with the large value of 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si9.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mi〉σ〈/mi〉〈mi〉w〈/mi〉〈/msub〉〈/mrow〉〈/math〉.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): Ermanno Cardelli, Riccardo Donnini, Antonio Faba, Simone Quondam Antonio〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We propose an experimental method for the identification of the crystal grain orientation in polycrystalline ferromagnetic materials with Goss texture. The grain orientation respect to the lamination plane is evaluated by a suitable contact-less vector measurement of the magnetic field under rotational polarization. First of all, the fundamental in-plane easy axis is detected. After that, the measured data are numerically processed, taking into account a cubic anisotropy grain model, suitably developed, in order to estimate the orientation of the other two crystal axes respect to the lamination plane. The comparison of the obtained results with Electron Back-Scattering Diffractometry (EBSD) measurements confirms the validity of the proposed approach. Multi-grain and single-crystal test specimens are analyzed in order to investigate the possibility to apply this method as on-line detection system.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 April 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 475〈/p〉 〈p〉Author(s): O. Baffa, R.H. Matsuda, S. Arsalani, A. Prospero, J.R.A. Miranda, R.T. Wakai〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The investigation of magnetic nanoparticles for medical and biological applications is relatively recent and steadily growing. When properly functionalized, magnetic nanoparticles (MNPs) can target cancer cells and deliver a drug or heat to these cells. MNPs are being investigated in several applications in medicine such as hyperthermia, magnetic particle imaging, cell separation and magnetofection〈em〉, in vitro〈/em〉 and 〈em〉in vivo〈/em〉 alternating current biosusceptibility, T1 and T2 magnetic resonance contrast agents, and magnetorelaxometry. In each of these applications, a specific physical property is measured. Magnetorelaxometry relies on the fact that when MNPs are magnetized they can relax by the Brownian and Néel mechanisms. Both mechanisms depend on the MNP size and for certain conditions can have a faster relaxation through the Brownian, compared to the Néel, mechanism. This can be exploited to target cells. For certain sizes, when an MNP is free to rotate in the biological fluids, they will relax faster than when attached to a cell. This can provide a high contrast for detection of magnetically-labelled cancer cells, making it possible to differentiate normal from cancer tissue. Until very recently SQUIDs were the main detectors employed to measure MNPs, but Optically Pumped Magnetometers (OPM) are now an attractive alternative. OPMs are smaller, do not need liquid helium, and are simpler to operate than SQUIDs. Here, we present the initial steps of the development of an OPM-based instrument to measure relaxation of MNP 〈em〉in vitro〈/em〉.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 April 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 475〈/p〉 〈p〉Author(s): Y. Zhong, V. Chaudhary, X. Tan, H. Parmar, R.V. Ramanujan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉(Nd〈sub〉1-x〈/sub〉Dy〈sub〉x〈/sub〉)〈sub〉2〈/sub〉(Fe,Co)〈sub〉14〈/sub〉B magnetic nanoparticles, in a range of Dy content from 0 to 0.6, were synthesized by a mechanochemical process. The influence of Dy substitution on the crystal structure and magnetic properties were studied. With increasing Dy content, the coercivity of (Nd〈sub〉1-x〈/sub〉Dy〈sub〉x〈/sub〉)〈sub〉2〈/sub〉(Fe,Co)〈sub〉14〈/sub〉B particles first doubled from 8.8 kOe (x = 0) to a high value of 17.8 kOe (〈em〉x〈/em〉 = 0.5), further increase of Dy content led to a slightly lower coercivity of 17.5 kOe (〈em〉x〈/em〉 = 0.6). (Nd〈sub〉0.8〈/sub〉Dy〈sub〉0.2〈/sub〉)〈sub〉2〈/sub〉(Fe,Co)〈sub〉14〈/sub〉B particles exhibited good thermal stability, with a thermal coefficient of remanence (α) of -0.053% and thermal coefficient of coercivity (β) of -0.348%. Reduced spin-reorientation temperatures (T〈sub〉SR〈/sub〉) of 105 K – 115 K were observed for (Nd〈sub〉1-x〈/sub〉Dy〈sub〉x〈/sub〉)〈sub〉2〈/sub〉(Fe,Co)〈sub〉14〈/sub〉B, for 〈em〉x〈/em〉 in the range of 0 to 0.2, making these compositions more attractive for cryogenic applications. Detailed analysis of the temperature dependent magnetic properties revealed that coercivity was controlled by nucleation of reversed magnetic domains.〈/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-S0304885318318572-ga1.jpg" width="340" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 472〈/p〉 〈p〉Author(s): L. Zhu, Y. Meng, X.B. Zhai, Y.G. Wang, S. Lan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The magnetic properties of a series of Fe-P-C amorphous alloys were investigated. Fe〈sub〉80〈/sub〉P〈sub〉13〈/sub〉C〈sub〉7〈/sub〉 shows the largest saturation magnetic flux density among all the Fe〈sub〉80〈/sub〉P〈sub〉20−〈/sub〉〈em〉〈sub〉x〈/sub〉〈/em〉C〈em〉〈sub〉x〈/sub〉〈/em〉 (〈em〉x〈/em〉 = 7–9) alloys, which is supported by the hyperfine field distribution. Synchrotron X-ray diffraction was performed to explore the underlying structure mechanism. It is found that Fe〈sub〉80〈/sub〉P〈sub〉13〈/sub〉C〈sub〉7〈/sub〉 amorphous alloy has a larger atomic volume accompanied by a larger first peak position value of the reduced pair distribution function compared with those of Fe〈sub〉80〈/sub〉P〈sub〉12〈/sub〉C〈sub〉8〈/sub〉 and Fe〈sub〉80〈/sub〉P〈sub〉11〈/sub〉C〈sub〉9〈/sub〉. The origin of the unusual magnetic behavior of Fe〈sub〉80〈/sub〉P〈sub〉13〈/sub〉C〈sub〉7〈/sub〉 is thought to be the large Fe-Fe bond length.〈/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-S0304885318324272-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): Takahiro Ogasawara, Jun-young Kim, Yasuo Ando, Atsufumi Hirohata〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Distorted Heusler compound of 〈em〉D〈/em〉0〈sub〉19〈/sub〉 Mn〈sub〉3〈/sub〉Ge polycrystalline films were studied in terms of their crystalline structures and antiferromagnetic behavior by varying annealing temperature and Mn-Ge composition. Although low temperature growth for 30 nm Mn〈sub〉3〈/sub〉Ge showed no diffraction peaks in X-ray diffraction patterns, high temperature growth over 773 K with Mn-rich composition is found to promote the (0001) orientation of 〈em〉D〈/em〉0〈sub〉19〈/sub〉 Mn〈sub〉3〈/sub〉Ge which resulted in the emergence of an exchange bias effect in Co〈sub〉0.6〈/sub〉Fe〈sub〉0.4〈/sub〉 ferromagnetic layer at 120 K. The exchange bias field of 12 Oe in Mn〈sub〉3.16〈/sub〉Ge film grown at 773 K were improved to 61 Oe by enriching Mn composition to Mn〈sub〉3.97〈/sub〉Ge. The average blocking temperature was measured to be at 150 K which is not as high as its reported Néel temperature of 390 K in the bulk state, however, further improvements are expected by doping additional transition elements.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 472〈/p〉 〈p〉Author(s): Yining Li, Peilin Zhang, Zhongbo He, Guangming Xue, Dinghai Wu, Sheng Li, Yudong Yang, Wei Zeng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Currently, most of the physics-based magnetization models for giant magnetostrictive actuator are complicated in their mathematical models. These complicated models pose considerable challenges for real-time control. Focus on the above issue, we proposed a fitting magnetization model using Arctangent function, as the inverse of the Arctangent function can solve it very quickly. This function was suitable to model the magnetic behavior of giant magnetostrictive actuator serving in an electronic controlled injector or other types of on-off valves. Applicable range of the model was determined through computing the maximum magnetic field. Then the deviations of the proposed fitting model and Jiles-Atherton model under different parameters were studied to verify the computing effects of the model. Then the effectiveness of the fitting model was verified by experimental results. With a high computing precision and a concise form, the proposed model shows great potentials for the real-time control of giant magnetostrictive actuators.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 472〈/p〉 〈p〉Author(s): Denisa Kubániová, Petr Brázda, Karel Závěta, Tomáš Kmječ, Mariana Klementová, Jaroslav Kohout〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The effects of annealing temperature (1000–1125 °C) and Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 mass fraction (0.3–0.5) in the initial mixture on the composition of ferric oxide polymorphs within the Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉/SiO〈sub〉2〈/sub〉 nanocomposite prepared by sol-gel method were investigated. The structural and magnetic properties of prepared samples were characterized in detail by combination of X-ray powder diffraction (XRPD), high-resolution transmission electron microscopy, magnetic measurements and a local probe technique - transmission Mössbauer spectroscopy (TMS). The optimal conditions for preparation of 〈em〉ε-〈/em〉Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 rich sample were established and ∼91% of the 〈em〉ε〈/em〉-phase was reached with the characteristic particle diameter of 25 nm. It was observed that with increasing mass fraction of Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 in the starting material, the optimal annealing temperature decreases, while the width of the particle size distribution tends to increase. The relative concentrations of the four present polymorphs derived from XRD and TMS are in very good mutual agreement.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 9 July 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials〈/p〉 〈p〉Author(s): Samir Bhatt, H.S. Mund, Kishor Kumar, Komal Bapna, Alpa Dashora, M. Itou, Y. Sakurai, B.L. Ahuja〈/p〉

Description: 〈p〉Publication date: 15 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 474〈/p〉 〈p〉Author(s): Vinay Sharma, Shashwat Shukla, Xi Shibo, R.V. Ramanujan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Current research on magnetocaloric materials (MCM) aims at developing low cost, environmentally friendly materials which can be manufactured by simple processes. We report the effect of high energy ball milling on the structural, magnetic and magnetocaloric properties of low cost Fe〈sub〉2.1〈/sub〉Cr〈sub〉0.9〈/sub〉Al alloys. The degree of structural order in the Fe-Cr sublattice was found to vary with milling time in a cyclic fashion at a milling speed of 600 rpm. This phenomenon was analyzed by a reaction rate model based on the stored energy during high energy milling. The sample possessed a B2 crystal structure before milling. Milling for 15 min. at 600 rpm induced structural changes to produce a L2〈sub〉1〈/sub〉 structure. Interestingly, the 15 min. milled sample exhibited ∼50% higher saturation magnetization (〈em〉M〈sub〉S〈/sub〉〈/em〉) compared to the value before milling. The relative cooling power (RCP) also increased to 300 Jkg〈sup〉−1〈/sup〉 at 5 T, compared to a value of 244 Jkg〈sup〉−1〈/sup〉 before milling. Extended X-ray absorption fine structure (EXAFS) studies revealed the emergence of short range order in the milled samples.〈/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-S030488531831059X-ga1.jpg" width="402" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): Sukhleen Bindra Narang, Amit Arora〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉La-Na co-substituted M-type Co-Ti-Mn barium hexaferrites Ba〈sub〉(1−2x)〈/sub〉La〈sub〉x〈/sub〉Na〈sub〉x〈/sub〉Fe〈sub〉10〈/sub〉Co〈sub〉0.5〈/sub〉TiMn〈sub〉0.5〈/sub〉O〈sub〉19〈/sub〉 (0.00 ≤ x ≤ 0.25) were synthesized by conventional solid-state method. The influence of La-Na doping on the magnetic properties was investigated through VSM (vibrating sample magnetometer). The room temperature hysteresis loops show that the saturation magnetization decreases from 55.667 emu/g for x = 0.00 to 44.768 emu/g for x = 0.25 sample. To determine the complex permittivity (ε〈sub〉r〈/sub〉 = ε′ – iε″) and permeability (µ〈sub〉r〈/sub〉 = µ′ – iµ″) in 18.0–26.5 GHz frequency range, a vector network analyzer was employed. Reflection loss (RL) values were simulated from the values of ε〈sub〉r〈/sub〉 and µ〈sub〉r〈/sub〉 acquired using transmission line theory. The minimum RL obtained for the sample x = 0.10 is −45.94 dB (99.997% signal absorption) with an absorption bandwidth of 8.33 GHz for 1.3 mm sample thickness. Thus, the synthesized hexaferrites can be utilised in electromagnetic shielding and radar stealth technology applications.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 472〈/p〉 〈p〉Author(s): Abbas Sharifi, Saber Yekani Motlagh, Homayoun Badfar〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Peripheral vascular diseases is one of the main causes of death in the world. It is disorders that cause the blood vessels to narrow, block, or spasm. Here, effects of two inclined rectangular permanent magnets field on heat transfer and flow characteristics of blood fluid in a channel, as a model of straight part of the aorta, has been investigated using FerroHydroDynamics (FHD) principles. Thermally and hydrodynamically fully developed flow is considered at the inlet of the vessel. Governing equations have been discretized using the finite volume method and the SIMPLE algorithm. Simulations have been carried out for different inclination angles of magnets and saturated magnetization. From the results, the magnetic field of two inclined magnets leads to increase heat transfer of blood fluid flow toward the walls. Moreover, major energy loss, arising from mean wall shear stress, is decreased but local or minor energy loss, arising from generated vortices, is increased. Furthermore, the formation of recirculation zones near the wall, where the magnetic drug can be trapped there for uptake to tissue, is observed.〈/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-S0304885318300507-ga1.jpg" width="262" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): Thana Sriviriyakul, Sara Bogren, Vincent Schaller, Christian Jonasson, Jakob Blomgren, Fredrik Ahrentorp, Patricia Lopez-Sanchez, Marco Berta, Cordula Grüttner, Lunjie Zeng, Mats Stading, Christer Johansson〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We show results of nanorheological studies of different concentrations of xanthan (non-Newtonian fluid) in water using magnetic nanoparticles (MNPs) together with the AC susceptibility (ACS) vs frequency method. For comparison we also show the ACS response for different concentrations of glycerol in water (Newtonian fluid). The ACS response is measured, and the data is modelled using dynamic magnetic models and different viscoelastic models. We study the ACS response (in-phase and out-of-phase ACS components) at different concentrations of xanthan in water (up to 1 wt% xanthan) and with a constant concentration of MNPs. We use MNP systems that show Brownian relaxation (sensitive to changes in the environmental properties around the MNPs). ACS measurements are performed using the DynoMag system. The Brownian relaxation of the MNP system peak is shifting down in frequency and the ACS response is broadening and decreases due to changes in the viscoelastic properties around the MNPs in the xanthan solution. The viscosity and the storage moduli are determined at each excitation frequency and compared with traditional macroscopic small amplitude oscillatory shear rheological measurements. The results from the traditional rheological and nanorheological measurements correlate well at higher xanthan concentration.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 472〈/p〉 〈p〉Author(s): G.A. Rudakov, K.B. Tsiberkin, R.S. Ponomarev, V.K. Henner, D.A. Ziolkowska, J.B. Jasinski, Gamini Sumanasekera〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We have demonstrated a simple, scalable, and low-cost method of producing superparamagnetic nanoparticles (SPNs) encapsulated in carbon nanocages (CNCs). These materials show a very high saturation magnetization and have the potential to find applications in various technologies, including a direct drug delivery, supercapacitors, catalysis, etc. Using a facile method, it was shown that via a simple annealing process of precursors based on a mixture of transition metal (TM) (TM: Ni, Co or Fe) salt (acetate) and citric acid, TM nanoparticles encapsulated in CNCs (TM@CNC) can be readily produced. Our study indicates, that Ni@CNC nanoparticles synthesized at temperatures 500 °C–600 °C are in the 3–4 nm size range and show superparamagnetic behavior while the annealing at 700 °C and higher temperatures leads to the ferromagnetic behavior due to a nanoparticle agglomeration through the Ostwald ripening mechanism. Further, the superparamagnetic Co@CNC nanoparticles synthesized at 600 °C show slightly larger, 4–5 nm, sizes but have much higher saturation magnetization compared to Ni@CNC nanoparticles synthesized at the same temperature making Co@CNC more sensitive to external magnetic field and more useful for direct drug delivery. Finally, for Fe-based precursor, the agglomeration occurs at much lower temperatures. The Fe@CNC nanoparticles synthesized at 600 °C are much larger, in the 10–100 nm size range, show only ferromagnetic behavior, and may be used for magnetic nanoparticle hyperthermia in cancer treatment. The magnetic properties of samples are found to correspond to the theoretical estimates of the critical size of single-domain particles in these TM systems.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): T.S. Anilkumar, Yu-Jen Lu, Huai-An Chen, Hao-Lung Hsu, Gils Jose, Jyh-Ping Chen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, we prepared a nano-vehicle for dual targeted (magnetic and ligand) and dual mode (photothermal/photodynamic) cancer therapy. For this purpose, magnetic photosensitive liposomes (MPLs) from 1,2-distearoyl-sn-glycero-3-phosphocholine, dimethyldioctadecyl ammonium bromide (DDAB) and cholesterol were prepared using solvent evaporation/hydration technique to encapsulate the photosensitizer indocyanine green (ICG) and citric acid-coated MNPs (CMNPs). Hyaluronic acid-polyethylene glycol (HA-PEG) was coated to the MPLs by self-assembly of HA-PEG on liposome surface through ionic interactions between negatively charged HA and positively charged lipid DDAB to fabricate HA-PEG-MPLs with ∼220 nm particle size. The HA-PEG-MPLs aqueous solution showed highly efficient photothermal effects as the solution temperature reaches 45 °C in 3 min after exposure to near infrared (NIR) 808 nm laser at 2 W/cm〈sup〉2〈/sup〉. The in vitro cell culture experiments after treating human glioblastoma cells (U-87MG) with HA-PEG-MPLs confirmed enhanced cytotoxicity after 4 min exposure to NIR laser. A xenograft tumor model from subcutaneously implanted U87MG cells in nude mice demonstrated accumulation of HA-PEG-MPLs at tumor sites. By combination with successive NIR laser treatment, tumor growth could be prevented and the tumor volume at the end of treatment was 12.7% that of the control. Excellent and consistent anti-tumor efficacy with laser + HA-PEG-MPLs treatment was also demonstrated from the survival rates of animals, in vivo bioluminescence imaging and histology of tumor sections.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): Sonam Perween, A. Rathi, P.D. Babu, Govind Gupta, B. Sivaiah, R.P. Pant, B. Gahtori, G.A. Basheed〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The effect of partial (1–3%) rare-earth Gadolinium doping in 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si39.gif" overflow="scroll"〉〈mrow〉〈mtext〉D〈/mtext〉〈msub〉〈mrow〉〈mn〉0〈/mn〉〈/mrow〉〈mrow〉〈mn〉22〈/mn〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mi mathvariant="normal"〉Mn〈/mi〉〈/mrow〉〈mrow〉〈mn〉3〈/mn〉〈/mrow〉〈/msub〉〈mtext〉Ga〈/mtext〉〈/mrow〉〈/math〉 hard magnet has been investigated in this work. The 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mi mathvariant="normal"〉Mn〈/mi〉〈/mrow〉〈mrow〉〈mn〉3〈/mn〉〈/mrow〉〈/msub〉〈mtext〉Ga〈/mtext〉〈/mrow〉〈/math〉 undergoes magnetic transition at 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si41.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mi mathvariant="normal"〉T〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="normal"〉c〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 ∼ 745 K, which decreases down to 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si49.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mi mathvariant="normal"〉T〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="normal"〉c〈/mi〉〈/mrow〉〈/msub〉〈mo〉∼〈/mo〉〈mn〉715〈/mn〉〈/mrow〉〈/math〉 K upon 1% Gd-doping with introduction of mixed Mn valence states, as revealed from XPS study. The hard magnetic behavior of 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mi mathvariant="normal"〉Mn〈/mi〉〈/mrow〉〈mrow〉〈mn〉3〈/mn〉〈/mrow〉〈/msub〉〈mtext〉Ga〈/mtext〉〈/mrow〉〈/math〉 has been observed in a wide temperature range (up to 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si41.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mi mathvariant="normal"〉T〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="normal"〉c〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉). More importantly, the partial Gd-doping significantly enhances the room temperature hard magnetic properties i.e. squareness ratio (〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si35.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mi〉m〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="normal"〉r〈/mi〉〈/mrow〉〈/msub〉〈mo〉/〈/mo〉〈msub〉〈mrow〉〈mi〉m〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="normal"〉s〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉), coercivity (〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si34.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mi〉H〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="normal"〉c〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉) and energy product (〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si20.gif" overflow="scroll"〉〈mrow〉〈mi mathvariant="italic"〉BH〈/mi〉〈msub〉〈mrow〉〈/mrow〉〈mrow〉〈mi mathvariant="normal"〉max〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉) from 0.43, 2.73 kOe and 0.39 MGOe (〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mi mathvariant="normal"〉Mn〈/mi〉〈/mrow〉〈mrow〉〈mn〉3〈/mn〉〈/mrow〉〈/msub〉〈mtext〉Ga〈/mtext〉〈/mrow〉〈/math〉) to 0.57, 4.25 kOe and 0.5 MGOe (〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si56.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mi mathvariant="normal"〉Mn〈/mi〉〈/mrow〉〈mrow〉〈mn〉2.97〈/mn〉〈/mrow〉〈/msub〉〈msub〉〈mrow〉〈mi mathvariant="normal"〉Gd〈/mi〉〈/mrow〉〈mrow〉〈mn〉0.03〈/mn〉〈/mrow〉〈/msub〉〈mtext〉Ga〈/mtext〉〈/mrow〉〈/math〉), respectively. The modified Stoner-Wohlfarth model and low-field minor loop analysis reveal the nucleation hardening mechanism for the magnetization reversal. The study proposes the partial rare-earth doping as a new approach to enhance the hard magnetic properties of rare-earth free hard magnets.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): Qingying Ye, Shuiyuan Chen, Shengkai Huang, Jinling Wu, Juyan Xu, Wenjing Wang, Weilin Fan, Zhigao Huang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Base on the Monte Carlo simulation and fast Fourier transformation micromagnetism (FFTM) method, the magnetic dynamic properties of defective Cobalt (Co) nanorings are studied. The simulated results indicate that the hysteresis loops of Co nanorings with small defect are similar to those of the symmetric nanorings. However, when the area of defect increases, the magnetization process of the defective Co nanorings is different from that of symmetric Co nanorings. It is found that the remanence (〈em〉M〈sub〉r〈/sub〉〈/em〉) of the system increases at first and then decreases with the increase of defect location. Nevertheless, there is a relative stable region in which M〈sub〉r〈/sub〉 almost do not change with the defect location varying when the defect is small. The simulated results are well analyzed through the evolution of spin-configurations (SCs) of the defective Co nanorings. The investigation about magnetic dynamic properties of the defective Co nanorings may provide reference for their application in high-density data storage.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): S.M. Kabbur, S.D. Waghmare, D.Y. Nadargi, S.D. Sartale, R.C. Kambale, U.R. Ghodake, S.S. Suryavanshi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We report the electric and magnetic properties of nanocrystalline Tb〈sup〉3+〈/sup〉 substituted Ni〈sub〉0.25〈/sub〉Cu〈sub〉0.30〈/sub〉Zn〈sub〉0.45〈/sub〉Tb〈sub〉x〈/sub〉Fe〈sub〉2−x〈/sub〉O〈sub〉4〈/sub〉, with x = 0.0–0.125 mol., step: 0.025 mol ferrites, synthesized by glycine assisted autocombustion route. The structural studies confirm the formation of spinel cubic structure for NiCuZn ferrites with the formation of agglomerated polydisperse grains. The presence of two intrinsic IR absorption bands of spinel lattice at ν〈sub〉1〈/sub〉 (760–768) cm〈sup〉−1〈/sup〉 and ν〈sub〉2〈/sub〉 (650–665) cm〈sup〉−1〈/sup〉 for NiCuZn ferrite system confirms the existence of tetrahedral-A and octahedral-B sites over which the cations are distributed in spinel lattice. Complex permeability measurements signified the decrease in the initial permeability due to spin canting and spin frustration by paramagnetic Tb〈sup〉3+〈/sup〉 ions. The frequency dependent dielectric constant of NiCuZn ferrites revealed dielectric dispersion behavior in accordance with Maxwell–Wagner model. The incorporation of rare earth element (Tb〈sup〉3+〈/sup〉) in NiCuZn ferrite at relatively lower sintering temperature (1173 K), significantly alters the structural and electromagnetic properties of the host material. Therefore, the present Tb〈sup〉3+〈/sup〉 substituted NiCuZn ferrite system with moderate electrical resistivity and soft magnetic properties are potential candidate for multilayer chip inductor (MLCI) component applications.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 1 August 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials〈/p〉 〈p〉Author(s): Kinnari Parekh, R.V. Upadhyay〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Reply to comments on our paper entitled ‘The effect of magnetic field induced aggregates on ultrasound propagation in aqueous magnetic fluid’ [J. Magn. Magn. Mater. 431 (2017) 74–78]. We show here that comments does not stand valid.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 472〈/p〉 〈p〉Author(s): Vlasta Zavisova, Martina Koneracka, Alena Gabelova, Barbora Svitkova, Monika Ursinyova, Martina Kubovcikova, Iryna Antal, Iryna Khmara, Alena Jurikova, Matus Molcan, Miloš Ognjanović, Bratislav Antić, Peter Kopcansky〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Magnetic iron oxide nanoparticles (MNPs) are one of the most promising types of nanoparticles for biomedical applications, primarily in the context of nanomedicine-based diagnostics and therapy. They are used as contrast agents in magnetic resonance imaging and magnetite cell labelling. Furthermore, they are promising heating mediator in magnetic hyperthermia-based therapy, and can serve as nanocarriers in targeted gene and drug delivery as well. In biomedical applications, coating plays an important role in nanoparticle dispersion stability and biocompatibility. However, the impact of nanoparticle surface chemistry on cell uptake and proliferation has not been sufficiently investigated. The objective of this study is to prepare magnetic nanoparticles with inner magnetite core and hydrophilic outer shell of surfactant, protein and polymers that are commonly used in biomedical research. MNPs were characterized in-depth by various physicochemical methods. Magnetic hyperthermia, applied to find out the influence of MNPs coating on heating characteristics of the samples, did not show any correlation between layer thickness and specific adsorption rate. To evaluate the impact of surface chemistry on cell proliferation and internalization, the human lung adenocarcinoma epithelial (A549) cells were utilized. Substantial differences were determined in the amount of internalized MNPs and cell viability in dependence on surface coating. Our results indicate that the surface chemistry not only protects particles from agglomeration but also affect the interaction between cell and MNPs.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 7 July 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials〈/p〉 〈p〉Author(s): A.F. Abu-Bakr, A.Yu. Zubarev〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The present work deals with theoretical study of magnetic hyperthermia produced by a system of magnetically interacting ferromagnetic particles, placed in a rotating magnetic field. Our results show that the interparticle interaction significantly enhances the intensity of the heat production; the thermal effect in the rotating field is greater than that in the linearly polarized field with the same amplitude and frequency.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 10 July 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials〈/p〉 〈p〉Author(s): M. Schulte, S. Steentjes, N. Leuning, W. Bleck, K. Hameyer〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The effect of manganese on high silicon alloyed electrical steel sheets has been investigated. Three alloys with different Mn content (0.20, 0.69 and 1.38 wt%) have been melted on a laboratory scale and processed to fully-finished electrical steel sheets with 0.5 mm thickness. The effect of Mn on the mechanical, microstructural and magnetic properties has been studied. The average grain size decreases as Mn content increases. The texture is hardly affected by a variation of Mn content but the material is strengthened with increasing Mn content by solid solution strengthening. Mn increases the electrical resistance, which results in lower core losses at higher frequencies.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): Nehru Boda, Gopal Boda, K. Chandra Babu Naidu, M. Srinivas, Khalid Mujasam Batoo, D. Ravinder, A. Panasa Reddy〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The Er/Sm-substituted nickel ferrite and Sm-substituted cobalt ferrite nanomaterials were synthesized via citrate-gel autocombustion technique. The diffraction pattern revealed the formation of cubic spinel structure. In addition, the structural parameters such as lattice constant (a), average crystallite size (D) and X-ray density (ρ〈sub〉x〈/sub〉) were also evaluated. The surface morphology was analyzed using field emission scanning electron microscope (FESEM) and transmission electron microscopes (TEM). Besides, the low temperature magnetic properties were studied using magnetization versus temperature (M−T) & magnetic field (M−H) curves. The obtained results attributed that the NiSm〈sub〉0.1〈/sub〉Fe〈sub〉1.9〈/sub〉O〈sub〉4〈/sub〉 (NSF) and NiEr〈sub〉0.1〈/sub〉Fe〈sub〉1.9〈/sub〉O〈sub〉4〈/sub〉 (NEF) samples exhibited the superparamagnetic property pertaining almost zero value of coercivity (H〈sub〉c〈/sub〉) and remanence (M〈sub〉r〈/sub〉) at 5 K & 300 K. Moreover, the superparamagnetic property was evidenced by zero-field cooled (ZFC) and field cooled (FC) curves. Interestingly, the CoSm〈sub〉0.1〈/sub〉Fe〈sub〉1.9〈/sub〉O〈sub〉4〈/sub〉 (CSF) sample performed the soft magnetic behavior with increase of temperature from 5 to 300 K by possessing certain numerical values of H〈sub〉c〈/sub〉 and M〈sub〉r〈/sub〉.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 29 September 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials〈/p〉 〈p〉Author(s): Benedikt Mues, Eva M. Buhl, T. Schmitz-Rode, Ioana Slabu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Magnetic nanoparticles (MNP) have been successfully used as additives for the fabrication of implants such as hernia implants or vascular grafts in order to enable their in-vivo visualization with magnetic resonance imaging (MRI). However, functionality and long term stability of such implants were not quantitatively assessed until now. Reliable assessment of functionality is related not only to the determination of MNP concentration, but also to the impact of aggregation and immobilization of MNP inside the implant material on the MRI signal. In this regard, novel models must be developed which describe the relation between proton relaxation and both MNP clustering and mobility of MNP inside the implants. In this study, we experimentally quantify the transverse relaxation dependence on MNP size and MNP clusters, confirming theoretical descriptions. We identify three MNP size ranges for which different proton relaxation trends occur: One for which relaxivity increases with size (up to approx. 75 nm), a second for which relaxivity is constant (from 75 nm to 130 nm) and a third for which relaxivity decreases (from 130 nm to 220 nm). Further, we describe the impact of gradual MNP immobilization in agarose gels on relaxivity for three MNP types representing either of the identified size ranges. For all MNP types, we observe an increase of relaxivity with agarose content up to an MNP type specific maximum value. The relative rise of relaxivity is higher for MNP with larger sizes. The highest increase of the transverse relaxivity from 240 mM〈sup〉-1〈/sup〉s〈sup〉-1〈/sup〉 to 1000 mM〈sup〉-1〈/sup〉s〈sup〉-1〈/sup〉 is achieved for MNP clusters after immobilization in a gel with 7 %(w/w) agarose. The effects of MNP clustering and immobilization on relaxivity are valuable information for the engineering of implants with different contrast properties in MRI. Further, the relation between MNP immobilization and relaxivity values may serve as a basis for future non-invasive assessment of changes in implant functionality by MRI measurements.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): Akihide Hosokawa, Kenta Takagi, Takahiro Kuriiwa, Yuki Inoue, Kimihiro Ozaki〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A newly developed isotropic Nd〈sub〉2〈/sub〉Fe〈sub〉14〈/sub〉B/α-Fe nanocomposite magnet was subjected to a series of investigations of its microstructure and magnetic properties. The performance of the optimally annealed sample was found to be 〈em〉H〈/em〉〈sub〉c〈/sub〉 = 9.7 kOe and 〈em〉σ〈/em〉〈sub〉sat.〈/sub〉 = 171 emu/g. Moreover, an attempt was made to produce anisotropic nanocomposite magnets by a high-pressure torsion (HPT) experiment performed at room temperature. The microstructural analyses by TEM in 2D and by FIB-SEM serial sectioning in 3D elucidated that the two-phases microstructure is not distorted homogeneously but shear bands (SBs) are formed. It was found that both the hard magnetic Nd〈sub〉2〈/sub〉Fe〈sub〉14〈/sub〉B and soft magnetic α-Fe phases are distorted significantly near those SBs even though the crystallographic orientations of the Nd〈sub〉2〈/sub〉Fe〈sub〉14〈/sub〉B grains are randomized therein. The relationships between this microstructure developed by HPT and the corresponding magnetic properties are discussed.〈/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-S030488531831607X-ga1.jpg" width="380" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 472〈/p〉 〈p〉Author(s): A.N. Grebenchukov, S.E. Azbite, A.D. Zaitsev, M.K. Khodzitsky〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉At the terahertz frequency range, 2D material graphene is the most promising candidate for using as a functional part of magnetooptical devices because of discovered giant Faraday rotation and ability to dynamical properties control. In this paper magnetooptical properties of graphene were investigated. Numerical analysis on graphene-dielectric structure have shown the tunability of Faraday rotation and ellipticity in terms of amplitude and frequency by optical pumping of different radiation power and wavelength. Our work demonstrates alternative way for developing ultrafast optically tunable polarization modulators of THz wave.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 473〈/p〉 〈p〉Author(s): Guannan Shi, Ryoji Takeda, Suko Bagus Trisnanto, Tsutomu Yamada, Satoshi Ota, Yasushi Takemura〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, we precisely calculated the specific loss powers (SLPs) of magnetic nanoparticles (MNPs) based on dynamic hysteresis measurements. The advantage of this evaluation method is that the intensity and frequency of the applied magnetic field can be varied over a wide range for samples of various condition. The results show that the coercive field and SLP of Resovist® increase by orienting the magnetic easy axes of the nanoparticles. The magnetic field was applied either parallel or perpendicular to the nanoparticle orientation. The area enclosed by the dynamic hysteresis curve was larger when the AC field was applied parallel to the nanoparticle orientation, indicating a greater increase in the hyperthermia temperature. This characteristic originated from the magnetic anisotropy energy of the nanoparticles and is in good agreement with our simulational results. The SLP of a solid sample with an aligned easy axis measured under an AC field of 4 kA/m, which was applied parallel to the axis, was more than two times that of a liquid sample. We also evaluated the SLPs of superparamagnetic 4-nm-diameter γ-Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 and ferromagnetic 20–30-nm-diameter Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 MNPs and compared them to that of Resovist®.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 6 August 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials〈/p〉 〈p〉Author(s): Victor V. Sokolov〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉It is pointed out that a recent article (Parekh and Upadhyay, 2017) is conceptually wrong. I have shown that authors (Parekh and Upadhyay, 2017) to obtained unreasonably good agreement between the calculated and the experimental data.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 4 September 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials〈/p〉 〈p〉Author(s): Sandeep Munjal, Neeraj Khare, Balasubramanian Sivakumar, Dasappan Nair Sakthikumar〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We report the hydrothermal synthesis of uniform size (∼6 nm) oleic acid capped CoFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 (OA-CoFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉) nanoparticles. These OA-CoFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 nanoparticles were initially hydrophobic and not dispersible in water which were transformed into hydrophilic nanoparticles by modifying their surface with citric acid using a rapid mechanochemical ligand exchange process, which makes CoFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 nanoparticles stable colloidal solution in water. The synthesized citric acid coated CoFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 (CA-CoFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉) nanoparticles show a high enough and stable zeta potential over 120 days. CA-CoFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 nanoparticles exhibited high biocompatibility under in vitro cell studies. The specific absorption rate (SAR) of the CA-CoFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 nanoparticles was measured by induction heating studies. Upon the exposure of AC external magnetic field, the viability of cancer cells was reduced considerably, suggesting efficient potentiality of these CA-CoFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 nanoparticles for Magnetic Hyperthermia Applications. Present mechanochemical ligand exchange method is proposed as an efficient method for large scale production of biocompatible and water dispersible magnetic oxide nanoparticles for Magnetic Hyperthermia Applications.〈/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-S0304885317329578-ga1.jpg" width="489" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 472〈/p〉 〈p〉Author(s): Alex van Silfhout, Ben Erné〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Colloidal stability in external magnetic field is crucial for applications of ferrofluids. Here, we introduce a magnetic analysis approach to monitor how rapidly magnetic nanoparticles are pulled out of the liquid in an external magnetic field gradient. The motion of the sedimentation front is deduced from the time-dependent field produced by a column of ferrofluid placed on a permanent magnet. Citrate-stabilized nanoparticles in a homemade aqueous ferrofluid are found to sediment at the rate expected of single nanoparticles. More rapid sedimentation occurs in two other types of ferrofluid, indicating that our magnetic sedimentation analysis method can differentiate ferrofluids with respect to their in-field colloidal stability. Our method is further validated by comparison with time-dependent X-ray transmission profiles.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 April 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Magnetism and Magnetic Materials, Volume 475〈/p〉 〈p〉Author(s): P. Arpaia, M. Buzio, O. Capatina, K. Eiler, S.A.E. Langeslag, A. Parrella, N.J. Templeton〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The twofold goals of this work are (i) to reduce the lack of experimental data in literature concerning the effects of temperature and mechanical strain on magnetic properties of the Ni-Fe alloy Cryophy, and (ii) to validate its use as magnetic shield material for last-generation cryomodule prototypes of crab cavities used in particle accelerators for transverse deflection. The relative magnetic permeability was measured at room and cryogenic temperature, and its lowest value at 4 K fits the minimum design criteria of 100,000 for the crab cavities experiment at CERN. Permeability after uniaxial plastic deformation between 0% and 3% was also measured by means of an Epstein frame. Results show that deformation induces a significant decrease in the magnetic performances, underlining that particular care must be taken during all stages of handling and operation. Finally, the attenuation inside the magnetic shields was tested for the prototype Super Proton Synchrotron at CERN. Results highlight that at 150 mm from the opening, the magnetic field is shielded as required.〈/p〉〈/div〉 〈/div〉