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Magnetics in Japan, IEEE Translation Journal on

Issue 7 • Date Oct. 1985

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Displaying Results 1 - 25 of 57
  • [Front cover]

    Page(s): c1
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  • List of Contributors

    Page(s): nil1
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  • [Breaker page]

    Page(s): nil1
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  • Table of contents

    Page(s): 781 - nil2
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  • Magnetic Properties and Magnetic Structure of Amorphous Oxides in the Fe3O4-CaO-SiO2 System

    Page(s): 783 - 784
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    Magnetic properties of amorphous Fe3O4-CaO-SiO2 are described in terms of the microscopic structure. The amorphous region and magnetization strengths for the system were determined, while measurements of the temperature dependence of magnetization revealed no clear Curie temperature; this was attributed to thermal decomposition of the ferrimagnetic crystalline phase. Mossbauer spectra indicated that the material was paramagnetic at room temperature and ferrimagnetic at 4.2 K. It was concluded that Fe3+ in octahedral sites, Fe3+ in tetrahedral sites and Fe2+ interact paramagnetically. View full abstract»

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  • Magnetic Properties of SrFe1-xCoxO3

    Page(s): 785 - 786
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    Mössbauer effect studies, magnetic measurements, and neutron diffraction analyses were performed to investigate the electronic state of SrFe1-xCoxO3. For 0. 2 ¿ x ¿ 1. 0 the compound is ferromagnetic, and as x decreases the magnetization increases linearly; extrapolation to x = 0 gives a magnetic moment of 3. 73 ¿B/F. U., close to that for a high-spin state in Fe4+. Mössbauer spectra also indicated a high-spin state for Fe4+ in the range 0 ¿ x ¿ 0.2. View full abstract»

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  • Property Channges of Fe-N Prepared by Reduction-Sintering Method with Heat Treatment

    Page(s): 787 - 788
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    While much is known about the large magnetic moment of Fe8 N thin films, little work has been done on bulk FeN material. Bulk FeN was prepared by pressure-forming ¿-Fe2O3 powder, reduction in H2 and sintering at 700 to 800°C in NH3-H2, followed by gradual cooling or by quenching from different temperatures. It was found that under appropriate conditions (sintering temperature 700°C, PNH3 = 0.5), this reduction-sintering process can be used to obtain stable single-phase Fe4N. Further studies on quenching and other heat treatment are underway to produce Fe8N from this Fe4 N material. View full abstract»

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  • Magnetics and the New Understanding of Materials Given by the New Frame in Physics

    Page(s): 789 - 790
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    A new framework uniting classical and quantum physics, along with implications for the study of magnetic materials, are discussed. Features of this framework include emphasis on the Schrödinger representation of time-dependent wave functions, which alone enables a continuous transition from classical to quantum mechanical phenomena, and the adoption of an "electron field" model, replacing the vortex ring model of the electron. Consequences for magnetics, such as in statistical thermodynamic treatment of magnetized materials and the manifest nature of the Meisner effect in superconductors, are indicated. View full abstract»

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  • Measurements of Hall Loop of GdCo and GdFe Amorphous Films with Perpendicular Magnetic Anisotropy Under Pulsed High Magnetic Field up to 40 T

    Page(s): 791 - 792
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    To better understand the magnetic structures of magnetically anisotropic GdCo and GdFe amorphous films, Hall characteristics were measured under strong pulsed magnetic fields up to 40 T. Anomalous magnetization loops were observed for GdCo and Bi-doped GdFe film, differing from data obtained for weaker fields, and changes in residual Hall voltage with the in-plane magnetic field were also determined. View full abstract»

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  • Polarity Reversal of Hall Voltage at Compensation Temperature in Amorphous RE-Ni (RE:Gd, Tb, Dy, Ho) Films with Perpendicular Magnetic Anisotropy

    Page(s): 793 - 795
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    Various amorphous rare earth - Ni (ferrimagnetic) films were prepared, and the temperature dependences of their Hall loops studied, to elucidate the mechanism by which the Hall polarity is suddenly reversed at the compensation temperature Tcomp. The polarity of VH was found to change from positive to negative at Tcomp in all cases, in contrast with RE-Co(Fe) films, which change from negative to positive. At temperatures below Tcomp, where the Gd spin dominates, ¿H ≫ 0, lending support to the hypothesis that the transition metal spin plays a dominant role in the Hall effect mechanism in RE-TM films. View full abstract»

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  • Magnetic Properties and Thermal Expansion of Fe-Tb Amorphous Alloys

    Page(s): 796 - 797
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    Measurements of the Curie temperature Tc, coercive force Hc, thermal expansion, and magnetoelasticity effects of Fe-Tb alloys in both film and bulk form, are reported. The compositional dependence of Hc was determined, and were found to be essentially the same for both film and bulk material. Anomalous thermal expansion curves, exhibiting either Invar effects or small expansion coefficients over a broad temperature range, were observed. Tc is slightly affected by the type of substrate and the temperature through the pressure effect, dTc/dP = ¿2 K/kbar. View full abstract»

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  • Estimation of the Local Magnetic Anisotropy Energy of Amorphous Rare Earth Based Alloys

    Page(s): 798 - 799
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    Studies to determine the local anisotropic energy D of rare earth atoms in amorphous TbFe, TbAg, and DyFe alloys through comparisons of experimental and calculated values for the Arrott plot coefficient at the Curie temperature were studied. Iterative calculations converging on a solution for the magnetization were used in determining the theoretical value of b for different local an isotropy energies D; this method was used to find the D for which the experimental and calculated values of b coincided. Values of D thus obtained ranged from 1.1 to 9.6 (× 1015 erg/atom). View full abstract»

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  • Magnetic Properties of Metastable Fe-Al Alloys Produced by Vapor Quenching

    Page(s): 800 - 801
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    Fe-Al alloys were prepared by the standard RF sputtering method (vapor quenching), their compositions were determined by EPMA, X-ray diffraction and Mössbauer effect analyses were performed, and film magnetic properties were measured. Sputtered alloys were in a nearly complete state of disorder. At higher Al concentrations, an amorphous phase appeared, and marked deviation from the simple dilution law governing the composition dependence of the magnetization was observed. The Mössbauer spectra of sputtered bcc films suggested the existence of a magnetic perpendicular anisotropy. View full abstract»

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  • Magnetic Properties of Metastable Fe-Cu Alloys Produced by Vapor Quenching

    Page(s): 802 - 803
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    Homogeneous metastable Fe1-xCux films were prepared by RF sputtering, and their magnetic properties investigated. X-ray diffraction showed a single bcc phase for x = 0 to 0.4, and a single fcc phase for x = 0.6 to 1.0; deviations from the simple dilution law for the magnetic moment were observed for both structures. Mössbauer spectra indicated a tendency toward magnetic perpendicular anisotropy in bcc samples, and the average magnetic hyperfine field Hhf decreased slowly with x for both bcc and fcc alloys. Sample distributions were almost completely random (homogeneous) even on a microscopic scale. View full abstract»

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  • Magnetic Image Effect in Superconducting Magnet and Magnetization Measurement

    Page(s): 804 - 805
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    The magnetic image effect (flux distortion due to the Meissner effect) in superconducting magnets (SCM's) was studied both theoretically and experimentally. Changes with temperature in the magnetic moment of a current loop coil (as measured by a VSM) were observed; sudden drops at 15 K and 7 K corresponded to the superconducting temperatures of Nb3Sn and NbTi used in the SCM. Experimental results for both image effects and residual magnetic fields agreed with calculations by the finite element method. The image effect tends to cause overestimation of susceptibility and underestimation of the magnetization. View full abstract»

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  • Shape Stability of Magnetic Fluid

    Page(s): 806 - 807
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    A study of the instability of a spheroidal droplet of magnetic fluid in a uniform magnetic field, without a gravitational field, is described. A droplet of ferrofluid was suspended in water or glycerin, the droplet minor axis was measured for fields up to 1.2 kOe, and the interfacial tension between the ferrofluid and the water or glycerin was determined. The ratio of the droplet major axis to the minor axis K¿1 increased with increasing field, and depended on the initial droplet diameter. The results could be explained by minimizing the sum of the magnetic energy and the surface energy with respect to K. View full abstract»

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  • Magnetic Properties of Layer Structure Compound La (CrxMn1-x)2Ge2

    Page(s): 808 - 809
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    The La(Mn1-xCrx)2Ge2 system (with a Mn-Ge-La-Ge-Mn layer structure) was studied in order to clarify the effect of the manganese 3d electrons, and to find properties with potential applications. Homogeneous single-phase samples were prepared, and the saturation magnetic moment Is per Mn atom at 4.2 K and Curie temperature Tc were determined as functions of Cr substitution x. Both Is and Tc decreased monotonically with x, and the system turns paramagnetic for x ≫ 0.5; similar results were obtained for Fe- and Co-substitution. An explanation in terms of a sharp decrease in the density of states of 3d electrons at Ef with Cr, Fe, or Co substitution may be possible. View full abstract»

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  • Czochralski Crystal Growth of Intermetallics Compounds by Use of a Tri-Arc Furnace

    Page(s): 810 - 811
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    Preparation of R5Ge3 single crystals by Czochralski growth in a tri-arc furnace is described. A rectangular polycrystal seed was fixed to a thermally isolated Mo rod in the furnace, and crystals pulling from a homogeneous melt. Growth of single crystals requires careful choice of the pulling speed, rotating speed, arc melting current and anode cooling rate, all of which vary depending on the compound. For instance, an Nd5Ge3 single crystal was successfully grown at a pulling rate of 0.8 mm/min and rotation rate of 6 rpm. View full abstract»

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  • Magnetic and Electrical Properties of Eu-Yb Alloy at High Pressure

    Page(s): 812 - 813
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    By regulating the pressure, the number of conduction electrons in EuxYb1-x alloy was varied to study the relation between number of conduction electrons and the Eu spin configuration through measurements of the magnetic transformation points Tc (ferro-para), Tt (spin glass-ferro) and Tg (spin glass-para), the magnetization and the electrical resistivity. At x = 0.025, increasing pressure leads to a transition to a semiconducting state, i.e. a decreasing number of conduction electrons. The transition points Tc and Tt changed considerably with pressure, the change in Tc being especially great for systems containing only rare earth elements, while Tg, where it existed, showed almost no pressure dependence. View full abstract»

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  • Magnetism Under High Pressure

    Page(s): 814 - 815
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    The magnetic properties of a number of materials under high pressure conditions were studied, and measurements at liquid helium temperatures and pressures of up to 35 kbars were conducted. Studies addressed the pressure effects on s and d band electrons in Ni-base alloys, competition between ferromagnetic and antiferromagnetic interactions in Fe2P and EuSe, and pressure-induced structural transitions in RAg (where R is a light rare earth element). View full abstract»

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  • δ-Dependence of Magnetism in the C15 Laves Phase System HfCo2

    Page(s): 816 - 818
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    Investigations of the magnetic properties of non-stoichiometric HfCo2+δ led to the discovery of ferromagnetism for δ ≫ 0.8. Homogeneous samples formed by plasma jet-melting in argon were annealed to obtain single phase crystals, and then quenched. X-ray diffraction confirmed the existence of a single-phase with C15 type structure for -0.2 ≪ δ ≪ 1.2, but a single phase could not be obtained at other compositions. The range of ferromagnetic behavior, susceptibility, and other magnetic properties are described. View full abstract»

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  • Magnetic Properties of Film Evaporated Simultaneously from Two Elements

    Page(s): 819 - 820
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    The composition distribution and magnetic properties of Fe-Cu film formed by two-source simultaneous evaporation at oblique incidence are described. Fe films were prepared under the same conditions as Fe-Cu films, and the ratio of magnetic moments of Fe atoms in Fe and Fe-Cu films measured. This ratio began decreasing with decreasing Fe content from around 50 percent Fe, reaching zero at about 15 percent Fe. Mössbauer spectra of samples formed at 10° and 45° incidence showed nonmagnetic lines for both, indicating the existence of ¿-Fe atoms. As such atoms exist only in areas with high Cu contents, this would imply inhomogeneous composition distributions in the columnar grains of Fe-Cu film. View full abstract»

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  • Thickness Dependence of Induced Magnetic Anisotropy in Evaporated Permalloy Films

    Page(s): 821 - 822
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    The uniaxial magnetic anisotropy (Ku) of evaporated Permalloy films of different thicknesses was measured. For thinner films, measurements relied on the magnetoresistive (¿R) effect. Although there was considerable scattering in the results, Ku tended to decrease as films were made thinner than 500 Å, and disappeared at around 100 to 300 Å. This decrease is thought to be related to the island structure of extremely thin films, in which case the anisotropy finally disappears in fine crystal grains of size arotund 100 Å. View full abstract»

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  • Magnetic and Diffusional Properties of Compositionally modulated Amorphous CoTi/CoNb Alloys

    Page(s): 823 - 824
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    Studies to determine the effects of alternating layers of positive-magnetostriction a-CoTi and negative-magnetostriction a-CoNb, to investigate the consequences for the film magnetic properties, and to elucidate the Nb-Ti interdiffusion mechanism, are described. Co80Ti20/Co80Nb20 and Co80Ti20/Co70Si15B15 films, compositionally modulated with wavelengths of 30 to 60 Å, were prepared by sputtering. The CoTi/CoNb coercivity was found to be increased compared with CoNb, CoTi, and CoNbTi films. The compositionally modulated structure changes to a simple periodic structure through low-temperature heat treatment, but this transition is apparently reversible at higher temperatures through some anomalous diffusion mechanism. View full abstract»

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  • Magnetic and Diffusional Properties of Compositionally Modulated Amorphous Fe(C)/Si Alloys

    Page(s): 825 - 826
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    Magnetic and diffusion properties of compositionally modulated a-Fe80C20/a-Si were investigated as functions of the modulation wavelength. It was found that 1) samples with 3.8-6.9 Å magnetic Fe(C) layers were paramagnetic at low temperatures; 2) when Fe(C) layers were separated by thick Si layers, the temperature dependence of the magnetization was linear; 3) samples with Fe(C) layers thicker than 18 Å showed a T3/2 temperature dependence of the magnetization; 4) wvhen Fe(C) thickness was held at 18 Å and the Si thickness varied, the Hc decreased with the modulation wavelength; and 5) Fe-Si interdiffusion was directly observed. View full abstract»

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Aims & Scope

IEEE Translation Journal on Magnetics in Japan is a publication of the IEEE Magnetics Society published between 1985 and 1994.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
James E. Opfer
Hewlett-Packard