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  • 1
    Electronic Resource
    Electronic Resource
    High-resistive, high-saturation inductive soft magnetic amorphous fluorine modulated (CoFe)BF films : 37th Annual conference on magnetism and magnetic materials (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 5586-5588 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: (Co0.5Fe0.5)BF amorphous films with modulated F content were investigated and such multilayered films have ceramic spacers to increase permeability at high frequencies. Modulated films having alternate F-poor layers (15 nm thick) and F-rich layers (5–10 nm thick) within an F content of 2–10 at. % were prepared by a sputtering technique. High-saturation induction (Bs) of 1.6–1.8 T, low coercivity (Hc) less than 1.0 Oe, permeability (μ') of 800–1000, and enhanced high frequency response were obtained in the case of a modulated film having alternating layers: 15-nm-thick layers, 2 at. % F, ρ=150 μΩ cm and 10-nm-thick layers, 10 at. % F, ρ=800 μΩ cm. The number of periods was variable. Auger-electron spectroscopy and secondary-ion mass spectroscopy depth profiles clarified the periodicity of the modulated films. Multilayered films with four layered F modulated films (0.55 μm/layer) and SiO2 spacers (0.24 μm/layer) exhibited an excellent frequency response of μ'=1500 in the range of 1–100 MHz. The coexistence of high ρ, high Bs, and low Hc in these films may be attributed to the oscillatory resistivity resulting from a compositional modulation in F and B.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.353659
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  • 2
    Electronic Resource
    Electronic Resource
    High frequency permeability of nanocrystalline Fe–Cu–Nb–Si–B single and multilayer films : The 5th Joint MMM−Intermag Conference (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 6238-6240 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Structure and magnetic properties of Fe–Cu–Nb–Si–B alloy single and multilayer films produced by rf sputtering have been investigated. The 1-μm-thick single films are of an amorphous phase in the as-sputter-deposited state and are crystallized into a mainly bcc phase with fine grains of nanometer size, as are melt-quenched ribbons with the same composition. The crystallization behavior and the Curie temperature of these single films are also similar to those of the ribbons. The crystallization-induced bcc phase possesses a high saturation magnetization of 1.3 T and good soft magnetic properties. For improving permeability at high frequency, an attempt has been made to multilayer the Fe–Cu–Nb–Si–B alloy with nonmagnetic materials such as SiO2. It has been found that Fe75.6Cu0.8Nb1.9Si13.2B8.5(500 nm)/SiO2(5 nm) multilayer films annealed at 500 °C for 1 h also consist of bcc fine crystallites and exhibit permeability as high as 7000 at 1 MHz and low coercivity of about 0.08 Oe.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350007
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  • 3
    Electronic Resource
    Electronic Resource
    Soft magnetic properties of composite-anisotropy CoNbZr/ceramics multilayers (invited) : 37th Annual conference on magnetism and magnetic materials (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 5580-5585 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: CoNbZr/ceramics multilayered films, the metal layers of which have sequentially changed anisotropy directions, were investigated. Such newly processed film is called "composite-anisotropy multilayer film.'' The effects of this new processing on soft magnetic properties were studied. In the case where the shift angle in the easy magnetization direction between neighboring CoNbZr layers is 45°, a smooth B-H loop with low coercivity was obtained. Furthermore, annealing from 200 to 400 °C resulted in high permeability (μ') of 1000–1500 and excellent frequency responses of μ' above 100 MHz in all directions in the plane of the film. These results could be explained in terms of magnetic interactions of the CoNbZr magnetic layers which are in close contact with one another across the intervening ceramics layers. These findings indicate that such composite film has many advantages over conventional uniaxial multilayers in applications to magnetic devices. Since these characteristics are thought to be very significant for microdevices composed of disc-shaped magnetic cores, we fabricated a planar microtransformer composed of circular spiral coils and disk-shaped magnetic cores, 2.4 mm in size, using photolithographic technology. The input–output voltage ratio, VOUT/VIN, was measured in the frequency range of 2–40 MHz and showed a high value of 0.83 at 40 MHz.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.353658
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  • 4
    Electronic Resource
    Electronic Resource
    Scanning tunneling microscopy investigation of single electron tunneling in Co–Al–O and Cu–Al–O granular films (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 6331-6333 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated single electron tunneling in Co–Al–O and Cu–Al–O granular films using scanning tunneling microscopy (STM). Topographic images show well-defined granular structures where nanometer-sized metal granules are embedded in insulating matrix. The Coulomb staircases in the current–voltage (I–V) curves are clearly observed even at room temperature in both films. For the Co–Al–O film, furthermore, negative differential conductance appears in the Coulomb staircase. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.372696
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  • 5
    Electronic Resource
    Electronic Resource
    Analysis of the green fraction of humic acids (1996)
    Oxford, UK : Blackwell Publishing Ltd
    European journal of soil science 47 (1996), S. 0 
    Details
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The green fraction of humic acids (HAs), Pg, was fractionated by gel chromatography on Sephadex G-50. Repeated chromatography of the crude Pg obtained by the first chromatography of HA yielded a sharp peak (G1) and two broad bands (G2) of purified Pg. The recovery of Pg in G1 and G2 as percentages of the total Pg content of the HA were 16.2 and 14.5%, respectively. Distinct peaks were detected at 615, 570, 450 and 280 nm in the UV-visible spectra of both G1 and G2 in alkali solutions. Estimates of weight-average molecular weight were 9.7 * 103 for G1 and 1.23 * 104 for G2. In the 1H-NMR spectra the percentage of hydroxyl groups of 4,9-dihydroxy-perylene-3, 10-quinone (DHPQ) nuclei, which are known to be the chromophore of Pg, was 4.1 and 4.5% of the total H, respectively. Based on these values and the H/C ratios, DHPQ-C was estimated as 28% of total C. 13C-NMR spectra obtained using inverse-gated decoupling yielded 40–41% aromatic C, which suggested the presence of aromatic rings other than DHPQ. All of the IR, 13C- and 1H-NMR spectra indicated that the two purified Pg samples largely differed from each other in their contents of alkyl and polysaccharide components.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2389.1996.tb01390.x
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  • 6
    Electronic Resource
    Electronic Resource
    Spin-dependent tunneling effect and GMR in metal–nonmetal granular systems (invited) (abstract) : The 40th annual conference on magnetism and magnetic materials (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 4733-4733 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Giant magnetoresistance (GMR, large negative and isotropic magnetoresistance) arising from a spin-dependent tunneling effect has been found in metal–nonmetal granular systems exhibiting extremely high electrical resistivities. These granular materials are reactively sputtered Co–(Al, Si)–O and Fe–Mg–O thin films, having a two phase nanostructure consisting of the Co (or Fe) rich metallic and magnetic grains and the Al (or Si,Mg) oxide narrow intergrains. These films possess large specific electrical resistivities(ρ0) of 104–106 μΩ cm at room temperature, and show remarkable magnetoresistance (Δρ/ρ0) whose values are about 8% in maximum at room temperature and at about 10 kOe of applied magnetic field. With decreasing temperature, Δρ/ρ0 and ρ0 increase. The temperature dependence of ρ0 can be expressed in terms of log ρ0∝T−1.2, and the electrical current versus applied electrical voltage does not follow the ohmic low. We consider that a spin- dependent tunneling conductance in the path of magnetic grains–nonmetallic intergrains–magnetic grains is responsible for the observed GMRs accompanying high electrical resistivities. The details of these transport properties and the related magnetization and structural properties will be presented. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.361655
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  • 7
    Electronic Resource
    Electronic Resource
    High-frequency magnetic properties in metal–nonmetal granular films (invited) : The 40th annual conference on magnetism and magnetic materials (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 5130-5135 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The structure and properties of Co–N and Co–O based films, prepared by rf magnetron reactive sputtering using nitrogen or oxygen and argon gases, have been studied. Transmission electron microscopy (TEM) observation reveals that each Co–(Al or Si)–(N or O) film is a typical film with granular structure, with grain size less than 5 nm. It is found by micro-focused energy-dispersive x-ray and electron energy loss spectroscopy analysis that the grains are mainly composed of Co and the intergranular regions are ceramics of N or O. In Co–N based films, soft magnetic properties are found in both Si and Al containing films over a wide range of film preparation conditions and compositions. Only the films with Al show soft magnetic properties in Co–O based films, which have ρ of 500–1000 μΩ cm, Hk of about 80 Oe and Bs of about 10 kG. By adding about 10 at. % Pd, the soft magnetic properties and Hk of Co–O based films are significantly improved, with Hk more than 180 Oe. These films exhibit a remarkable constant frequency response of the permeability up to around 500 MHz, which is approximately explained by the Landau–Lifshitz formula. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.361531
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  • 8
    Electronic Resource
    Electronic Resource
    Magnetoresistance and phase decomposition in Cr-Fe bulk alloys (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 5843-5849 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report magnetoresistance in Cr-Fe bulk alloys and its variations associated with the microstructure change due to the phase decomposition. Large negative magnetoresistance (MR) is observed in the as-quenched Cr-Fe bulk alloy at liquid helium temperature, but not at room temperature. This is attributed to the spin cluster glass in the homogeneous solid solution. A unique feature of the MR in these homogenous alloys is that it does not saturate even in the presence of very high magnetic fields. However, such MR behavior changes when ferromagnetic particles precipitate by annealing. A lower degree of compositional fluctuation of Fe progresses by annealing the alloy at 773 K for 400 h and then a higher degree of decomposition occurs after a prolonged aging for 2600 h. In the annealed specimens, MR is observed even at room temperature. The MR change becomes more prominent at a lower field region, since ferromagnetic particles precipitate from the solid solution. The degree of the phase decomposition of the Cr-Fe solid solution is quantitatively evaluated by the atom probe analysis, and the origin of the MR dependence on the annealing conditions is discussed. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.359165
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  • 9
    Electronic Resource
    Electronic Resource
    Giant magnetoresistance in sputtered Cr-Fe heterogeneous alloy films : The 6th joint magnetism and magnetic materials (MMM)-intermag conference (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 6790-6792 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have observed large negative magnetoresistance (MR) in Cr-Fe heterogeneous alloy films sputter deposited on heated substrates. The largest MR, 37.3% at 4.2 K and 14 T, appears around the Fe concentration of 20 at. %. While a large substrate temperature dependence of MR is observed when the Fe concentration is lower than 20 at. %, MR does not vary noticeably with changes in the substrate temperature when Fe concentration exceeds 20 at. %.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.358131
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  • 10
    Electronic Resource
    Electronic Resource
    Artificial fabrication of an L10-type ordered FeAu alloy by alternate monatomic deposition (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 1016-1018 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An FeAu ordered alloy has been fabricated artificially by depositing alternately monatomic layers of Fe and Au. Neither intermediate phase nor intermetallic compound is known for the Fe–Au system in the equilibrium state. Nevertheless, the x-ray diffraction for prepared FeAu films shows definite superlattice lines corresponding to the L10 ordered structure, and it is metastable at room temperature. The obtained FeAu ordered alloy is ferromagnetic, and it has the Fe moment of 2.5±0.3 μB, a considerably high Curie temperature over room temperature, and a large uniaxial magnetic anisotropy perpendicular to Fe and Au atomic planes. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.114715
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