日本応用磁気学会誌
Online ISSN : 1880-4004
Print ISSN : 0285-0192
ISSN-L : 0285-0192
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23 巻, 1_2 号
選択された号の論文の218件中151～200を表示しています
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7.2 Oxides
  • Insulator to Metal Transitions in Nd0.7(Sr0.3-yCay)MnO3
    J. G. Lin, C. Y. Huang, R. S. Liu, C. B. Wu, Y. S. Wang, W. N. Kan
    1999 年 23 巻 1_2 号 p. 528-530
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.528
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    We have measured the temperature dependent resistivity of Nd0.7(Sr0.3-yCay)MnO3 in the magnetic field up to 8 tesla, with y = 0 to 0.3 to investigate the stress-related insulator to metal (I-M) transitions. For samples with x = 0 and 0.1, the I-M transition occurs near the Curie temperature Tc, while for y = 0.2, the I-M transition temperature is much lower than Tc. No I-M transition is observed for y = 0.25 and 0.3, though there exists Tc in these two samples. Our results of the size-effect and the field dependency of the I-M transition can be explained by a combined action of the spin-dependent potential fluctuation and the magnetic interaction of the conduction electron with the localized spins.
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  • Electron Spin Resonance Study on CMR Oxides
    R. Gundakaram, J. G. Lin, C. S. Lee, P. C. Kuo, C. Y. Huang
    1999 年 23 巻 1_2 号 p. 531-533
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.531
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    Electron spin resonance (ESR) measurements have been performed on samples of the systems Pr0.7Sr0.3-xCaxMnO3 and Pr0.6Sr0.4-yCayMnO3. Substitution of Ca in the Sr site changes the effective ionic radius of the A-site without altering the average Mn valence. The variation in the resonance linewidth and the activation energy as a function of Ca content is presented and the observed features are explained on the basis of the change in the tolerance factor.
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  • Crystallization and Mössbauer Studies of Y3-xLaxFe5O12 (x=0.0, 0.25, 0.5, 0.75, 1.0)
    Chul Sung Kim, Young Rang Uhm, Jae-Gwang Lee
    1999 年 23 巻 1_2 号 p. 534-536
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.534
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    Magnetic and structural properties of garnet Y3-xLaxFe5O12(x= 0.0, 0.25, 0.5, 0.75, 1.0) have been studied by using X-ray diffraction, Mössbauer spectroscopy, and vibrating sample magnetometer. Polycrystalline cubic powders have been prepared by a metal-salt routed sol-gel method. Mössbauer spectra of Y3-xLaxFe5O12 have been taken at various temperatures ranging from 12 to 700 K. The lattice parameter increases linearly with increasing La concentration and follows Vegard's law approximately. Magnetic hyperfine fields of Y2.5La0.5Fe5O12 at 12 K are found to be 543 kOe (octahedral site) and 469 kOe (tetrahedral site). The values of the isomer shifts show that all of iron ions are in the ferric (Fe+3). The Curie temperature. Tc, is found to depend strongly upon La concentration. i.e., 578 K for x=0 and 625 K for x=0.5. The dependence of the Curie temperature suggests that the strengthen of superexchange interaction by La-O-Fe link is stronger than that by Y-O-Fe link.
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7.3 Amorphous & Nanocrystalline Magnetism
7.4 Superlattices, Ultrathin Films & Fine Particles
  • Perpendicular magnetic anisotropy of exchange coupled Co/Cu/Ni/Cu/Si(001) structures
    G. Lauhoff, J. Lee, W. Y. Lee, A. Hirohata, A. Samad, J. A. C. Bland, ...
    1999 年 23 巻 1_2 号 p. 572-574
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.572
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    Polar magneto-optic Kerr effect (MOKE) measurements on epitaxial Cu/22ACo/0-49Å Cu/53Å Ni/Cu/Si(001) structures reveal that the Ni magnetisation is aligned in-plane for zero Cu spacer layer thickness and becomes increasingly aligned out-of plane with increasing Cu spacer layer thickness, whereas an in-plane remanence for Co is always observed. Polarised neutron reflection (PNR) measurements at room temperature yield at room temperature a slightly reduced magnetisation of 1.57 ± 0.08μB for Co and 0.50 ± 0.04μB for Ni for a Cu/22Å Co/10Å Cu/53Å Ni/Cu/Si(001) structure. PNR measurements yield also a reduced in-plane remanence for both Co and Ni. This could suggest either a canted magnetisation or multidomain state at remanence. The Latter mechanism is supported by magnetic force microscopy images.
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  • Magnetic Critical Behavior of γ-Fe/Cu Multilayer
    Y. Yamada, B. Sadeh, C. Lee, M. Doi, M. Matsui
    1999 年 23 巻 1_2 号 p. 575-577
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.575
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    Ferromagnetic moment, a magnetic critical exponent β and Curie temperature (TC) of γ-Fe/Cu multilayer (0.8 to 7.2 ML Fe thickness) prepared by the molecular beam epitaxy (MBE) method have been investigated. The crystal structure of γ-Fe layer is distorted tetragonally (c/a>1) for the Fe thickness less than 4.5 monolayer (ML) and cubic for thicker films. Magnetization (M) of γ-Fe is increased with decreasing Fe layer thickness because of the increase of the ratio of high spin state γ-Fe atoms to total Fe atoms at interfaces. A critical exponent in a relationship M/MS = (1-T/TC) β, is estimated to be 0.30±0.02. TC is decreased with decreasing Fe layer thickness. The behavior is explained by taking into account of the number of nearest neighbor Fe atoms around an Fe atom.
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  • Magnetic Anisotropy, Interfacial Hybridization, and Orbital Magnetic Moment in Co/Pt Multilayers
    N. Nakajima, T. Koide, T. Shidara, H. Miyauchi, H. Fukutani, A. Fujimo ...
    1999 年 23 巻 1_2 号 p. 578-580
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.578
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    The interfacial magnetic and electronic states of Co/Pt multilayers have been studied by soft x-ray magnetic circular dichroism (SXMCD) measurements. The Co L2, 3 and M2, 3 SXMCD data reveal a strongly enhanced perpendicular Co orbital moment in multilayers which show perpendicular magnetic anisotropy (PMA). Large SXMCD signals were observed also at the Pt N6, 7 and O2, 3 edges, showing a strong interfacial Pt 5d-Co 3d hybridization. Evidence is presented for a transition from fcc to hcp Co with increasing Co-layer thickness. All these observaed effects are shown to drive PMA.
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  • Structure and Magnetic Properties of [Ag/Ni/Au] and [Au/Ni/Ag] Superlattices
    Yasuhiro Kamada, Hitoshi Kasai, Toshiki Kingetsu, Masahiko Yamamoto
    1999 年 23 巻 1_2 号 p. 581-583
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.581
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    The interface structure and magnetic properties of the two kinds of superlattices, [Ag/Ni/Au] and [Au/Ni/Ag] consisting of the same kind of atomic species and the reverse deposition sequences have been investigated. In the [Ag/Ni/Au] superlattice, the in-plane lattice constant changed continuously in the Ni on Au, and the large lattice strain is contained in the Ni layers and mixing region exists at the interface of Ni on the Au. On the other hand, in the [Au/Ni/Ag] superlattice, the in-plane lattice constant changes dis continuously and little strain is contained. The [Ag/Ni/Au] superlattice containing mixing region shows smaller magnetization than the [Au/Ni/Ag] superlattice. The [Ag/Ni/Au] superlattice containing more elastic strain than the [Au/Ni/Ag] superlattice shows larger magnetic anisotropy.
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  • First-Principles Calculation of the Structural and Magnetic Properties of (Cr, Mn, Fe)/Ag Monatomic Multilayers
    Jian-Tao Wang, Zhi-Qiang Li, Yoshiyuki Kawazoe
    1999 年 23 巻 1_2 号 p. 584-586
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.584
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    The structural and magnetic properties of (Cr, Mn, Fe)/Ag monatomic multilayers with the tetragonal L10 ordered structure in paramagnetic, ferromagnetic and three antiferromaenetic states are studied by means of the self-consistent full-potential linearized augmented-plane-wave method. By total energy minimization, the lattice constants for their ground states are estimated. It is found that the L10 ordered Cr/Ag has an AF1-type antiferromagnetic ground state kith a large local moment 3.30μB of Cr, the L10 ordered Mn/Ag has an AF2-type antiferromagnetic ground state with a large local moment 3.63μB of Mn, and the L10 ordered Fe/Ag monatomic multilayer has a ferromagnetic ground state with an enhanced moment 2.75μB of Fe.
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  • The Magnetism and Electronic Structures of Rh Monolayer
    L. H. Cho, K. S. Yoon, J. I. Lee
    1999 年 23 巻 1_2 号 p. 587-589
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.587
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    Recent Auger electron spectroscopy experiment suggested the possibility of magnetism in Rh overlayer on Cu(001). This experimental result was verified by our theoretical study on Rh monolayer on Cu(001). However the calculated total energy difference between para- and ferromagnetic states was found to be very small and it calls for the investigation of another state, i. e., the antiferromagnetic state. The dependence of total energies on the lattice constant was calculated for three magnetic states, i. e., para-, ferro-, and antiferromagnetic ones. It was found that there is no meaningful energy difference between para- and antiferromagnetic states for all the lattice constant. The ferromagnetic state is most stable compared to other states for the lattice constant greater than 6.68 a.u. The energy minima was found at the lattice constant of 6.57 a.u. where it is paramagnetic.
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  • On the Metastable States of Low Dimensional Magnetic Systems
    Q. Sun, Y. Hashi, L. Zhou, Q. Wang, J. Z. Yu, Z. Zeng, Y. Kawazoe
    1999 年 23 巻 1_2 号 p. 590-592
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.590
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    A special attention is paid to the dependence of magnetic state on the initial state in self-consistent solution of Kohn-Sham equation for low dimensional magnetic systems. Taking Fe3, Fe3Rh clusters, Nb(001) and Nb(110) monolayers as examples, the possible metastable states have been explored by using the discrete variational method (DVM) and self-consistent full-potential linear-augmented-plane-wave method (FLAPW), respectively. It is concluded that in the ab initio calculations if the self-consistent iterations do not start close enough to the real magnetic solution, the correct magnetic solution may not be found.
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  • Growth and magnetism of Ru films on graphite
    C. Binns, S. H. Baker, K. W. Edmonds, P. Krüger, J. C. Parlebas, ...
    1999 年 23 巻 1_2 号 p. 593-595
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.593
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    We report a study of growth and magnetism of Ru films on the graphite surface for substrate temperatures T of 70 K and 300 K using C 1s photoemission and surface reflectivity in the extreme ultraviolet region. The films consist of islands with a thickness of the order of 10 nm. The islands grow mainly laterally in size or number until a transition point where they fill about 40% (T = 70K) or 30% (T = 300 K) of the film volume. Then this fraction remains nearly constant suggesting a purely vertical growth of the islands. For a film grown at T = 70 K until the transition point, no linear dichroism could be observed, indicating that the Ru film was not ferromagnetic.
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  • Synthesis and the Magnetism of the Metal Halide-based Organic/Inorganic Layered Perovskite
    Y. Ando, E. Shikoh, T. Miyazaki
    1999 年 23 巻 1_2 号 p. 596-598
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.596
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    Metal halide-based layered perovskites, (RNH3)2MCl4, self-organized organic/inorganic multilayer structure were synthesized, where R is a simple alkylammonium molecule with a long chain length, (CH3(CH2)17) or a l-methyl-naphthalene (C10H9CH2), M is 3d transition metal elements. Its layered pcrovskite structure was checked by a FT-IR method. The perovskites of CH3(CH2)17NH3 with Cu and Cr showed ferromagnetism (TC= 10 K and 42 K, respectively), and Mn and Fe antifcrromagnetism (TN=41 K and 95 K, respectively). These results roughly corresponded to the results for methyl and ethyl ammonium complexes reported. The naphthlene complex with Cu also showed ferromagnetism, however, the Curie temperature became low. It was considered that the relative large chromophore might disturb the Jahn-Teller distortion of CuCl6 octahedra. l-methyl-naphthylamine- hydrochloride was luminous with the wavelength of 350 nm under ultraviolet light irradiation, but its Cu complex was quenched.
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  • Structure of Spin Vortices in Ultra-Thin Ferromagnetic Films
    E. Hirota, R. Nakane, M. Sawamura, S. Chikazumi, K. Mukasa
    1999 年 23 巻 1_2 号 p. 599-601
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.599
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    Structures of a spin vortex i.e., a circular distribution of the magnetization in ultra-thin ferromagnetic films are studied by micromagnetics analysis. The size and the magnetization of a spin vortex are given by the exchange stiffness constant, anisotropy constant and magnetization of the films. The structural changes and the magnetic hysteresis loop in the perpendicular magnetization process are also calculated.
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  • Magnetic Properties of Carbon Fine Particles Prepared in He Plasma
    Shin Akutsu, Yoshio Utsushikawa
    1999 年 23 巻 1_2 号 p. 602-604
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.602
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    In this study, the authors examined the correlation among the crystal structure, the unpaired electron and the magnetism of the carbon fine particles. From the result of X-ray diffraction, it is understood that the saturation magnetization of the carbon fine particles is influenced by degree of crystallinity, when the degree of crystallinity is 3.62%. the saturation magnetization is 8.5×10-7Wb·m/kg. From the ESR spectrum, the g-factor of the carbon fine particles is 2.0023 and the magnetism of the carbon fine particles may be due to the spin of the electron. Electron spin density of the carbon fine particles is 1.6×1022 kg-1. It is understood that the electron spin density of the carbon fine particles is increased by 1.5times compared with that of the graphite.
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Chapter 8. Magnetization Process
  • Microwave Magnetic Envelope Solitons in Thin Ferrite Films
    Carl E. Patton, Pavel Kabos, Hua Xia, Pavel A. Kolodin, Hong-Yan Zhang ...
    1999 年 23 巻 1_2 号 p. 605-610
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.605
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    Research on microwave magnetic envelope (MME) solitons in thin yttrium iron garnet films has revealed important new physics about this important class of nonlinear wave packet excitations. Soliton pulse energy measurements and energy decay have been used to understand the special decay properties for these solitons. The phase profiles of the pulses provide for positive identification of solitons. Threshold power measurements vs. input pulse width yield the soliton order. The soliton velocity is also power dependent, with characteristic plateaus which also relate to soliton order. These MME solitons may be modeled accurately through the nonlinear Schrödinger equation, provided care is taken to use accurate film and excitation parameters and take into account the frequency filtering inherent in the magnetostatic waves which make up the solitons. Special techniques have also been used to observe soliton collisions, generate decay free trains of solitons, and amplify solitons.
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  • Effect of Substitutional Elements on the Natural Resonance Frequency of Barium M-Type Ferrite
    S. Sugimoto, K. Okayama, H. Ota, M. Kimura, Y. Yoshida, H. Nakamura, D ...
    1999 年 23 巻 1_2 号 p. 611-613
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.611
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    The effect of substitutional elements (Ti, Sc, Zr, Ti0.5M0.5, Zr0.5M0.5, Sn0.5M0.5 (where M = Co, Ni, Zn, Mn, Mg, Cu)) on the natural resonance frequency of Barium M-type hexagonal ferrite (BaFe12O19) was investigated, with the aim of finding a material suitable for use as a microwave absorber in the GHz range. It was found that the anisotropy field (HA) decreases with increasing amounts of substitutional element, which leads to the natural resonance frequency (fr) and the matching frequency (fm) shifting to lower values. Some Ti0.5M0.5 substituted samples exhibited values of fr within the 1 to 20 GHz range, and the minimum reflection loss (R. L. ) for these samples was found to be less than -20dB. In particular, because of their large values of magnetic loss ((μ") =4.6 and μ" =4.0), the BaFe9(Ti0.5Mn0.5)3O19 and BaFe9.5(Ti0.5Mn0.5)2.5O19 samples had small matching thicknesses (dm) of 0.58mm and 0.53mm, with matching frequencies (fm) of 12.35GHz and 15.75GHz, respectively. Therefore, it may be concluded that Barium M-type ferrite is a candidate for use as a microwave absorber in the GHz range.
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  • The Effective Field in Ferromagnetic Uniaxial Thin Films
    Horst Hoffmann
    1999 年 23 巻 1_2 号 p. 614-616
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.614
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    The effective field determines the magnetic resonances as given by the Landau-Lifshitz equation. Real films include defects, responsible for the magnetic ripple. This gives additional contribuions to the homogeneous effective field. Especial at low applied fields these contributions cannot be neglected. They are of the same order of magnitude or even larger than the ideal effective field of homogeneous films.
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  • Analysis of Hysteresis loops at different temperatures for melt-spun Nd13Fe77B10
    Jin Hanmin, Y. B. Kim, Wang Xue-feng
    1999 年 23 巻 1_2 号 p. 617-619
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.617
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    Hysteresis loops of melt-spun Nd13Fe77B10 were measured in the temperature range between 4.2 K and 250 K. With increase of temperature, iHc increases to a maximum at the spin reorientation temperature Ts and then decreases. The loops and the spin distributions were calculated by the micromagnetic finite element method. The exchange interaction across the grain boundary was estimated to be about 90 % of that within a grain. The calculations reproduce the experiment well. The weaker the exchange interaction across the grain boundary, the smaller the iHc below Ts and the larger the iHc above Ts, and so the Stoner-Wohlfarth model provides the theoretical lower and upper limits of iHc below and above Ts, respectively. The magnetization proceeds by the non-coherent rotation and the spin distribution becomes quite nonuniform when the field decreases to around -iHc.
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  • Thermomagnetization Curves and Atomic Short-Range Order for Ni-Mn Alloys
    T. Miyanaga, T. Okazaki, Y. Aono, S. Ikeda, H. Kon
    1999 年 23 巻 1_2 号 p. 620-622
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.620
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    The thermomagnetization curves of Ni1-xMnx (x=0.20-0.23) alloys rapidly quenched and annealed at some conditions, in which there are variations in the atomic arrangement, were measured in order to reveal the relation between the magnetism and the atomic arrangement. The atomic short-range order parameter was determined from extended X-ray absorption fine structure (EXAFS) spectroscopy for Ni0.79Mn0.21 and Ni0.80Mn0.20 in which the short-range order cannot be obtained from X-ray diffraction technique. The magnetism of these alloys strongly depends on the number of nearest-neighbor Mn atoms around a Mn atom.
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  • Magnetism and Nano-cluster in Inhomogeneous Phase of Ni-Mn Alloy
    T. Okazaki, T. Miyanaga, Y. Kondo, Y. Aono, M. Homma
    1999 年 23 巻 1_2 号 p. 623-625
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.623
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    Ni3 Mn and Ni0.77Mn0.23 alloys which are ordered at 420°C have inhomogeneous phase, where long-range ordered magnetic domains distribute in a disordered non-magnetic matrix. Magnetism of these alloys with long-range ordered parameter S from 0.13 to 0.44 shows a ferromagnetic and a glass-like phases below and above the Curie temperature, respectively. The ferromagnetic cluster size obtained by magnetic analysis of the glass-like phase for those alloys is 13∼33 nm3 and increases width S. Minimum cluster size which forms a single domain is about 13 nm3. Magnetism of alloy in which the volume fraction of ordered region is greater than 0.32 (cluster size > 33 nm3), is wholly ferromagnetic.
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  • Magnetic properties of Ni2+xMn1-xGa (shape memory alloys)
    N. Perov, A. Vasil'ev, M. Matsumoto, T. Takagi, J. Tani
    1999 年 23 巻 1_2 号 p. 626-627
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.626
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    The magnetic properties of Ni2+xMn1-xGa (x=0.05, 0.1, 0.13, 0.14, 0.16, 0.17, 0.18, 0.19 and 0.2) shape memory alloys were measured in the temperature range from 130K up to 520K. For the composition with x=0.18 the Curie temperature and magnetization of saturation have a minimum. Besides thermal hysteresis of magnetization was found.
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  • Short Amorphous Micro-Wires Magnetic Properties and Structure.
    N. Perov, A. Radkovskaya, N. Usov, L. Zakharchenko
    1999 年 23 巻 1_2 号 p. 628-630
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.628
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    We present the results of the investigations of magnetic properties of the amorphous Fe- and Co-based wires with different magnetostriction depending on their length ( 8mm < L < 28 mm). For a Co-based wires it is estimated a critical wire length L*, for L<L* the influence of demagnetization fields on the wire magnetization is substantial and the wire remanent magnetization is in proportional to the square of the wire length. At cross remagnetization it was found the oscillations of the magnetic moment component along the wire axis.
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  • Magneto-optical investigation of near-surface micro-magnetic structure of FeNbCuSiB alloys
    E. E. Shalyguina, N. I. Tsidaeva, L. M. Bekoeva
    1999 年 23 巻 1_2 号 p. 631-633
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.631
    ジャーナル オープンアクセス
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    The results on the investigation of near-surface micro-magnetic structure of the as-cast and annealed at 550°C for 1hr FeCuNbSiB ribbons are presented. The measurements were performed by using of the magneto-optical micro-magnetometer having the spatial resolution up to ∼0.3μm. The as-cast samples were amorphous and the annealed samples had nanocrystalline structure with typical grain sizes of 10-12 nm. The dispersion of magnetic anisotropy was discovered in the studied samples. As result, their local magnetic properties were inhomogeneous. The linear size of the magnetic inhomogeneities in the as-cast and annealed samples was equal to ∼ 120-150 and ∼ 50-70 μm, respectively. It was established that in the annealed samples the local initial magnetic permeability increases and the coercivity decreases (up to 10 times) with respect to those of the ascast samples.
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  • The Large Gyromagnetic Effect in FeSiB Amorphous Wires
    Horia Chiriac, Catalin Sandrino Marinescu, Tibor-Adrian Óv&aacu ...
    1999 年 23 巻 1_2 号 p. 634-636
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.634
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    Results on the large gyromagnetic effect observed in FeSiB amorphous wires are reported. This effect consists in the appearance of a sample rotation around its axis. with frequencies from 1 to 60 Hz, when the sample is subjected to an axial alternating field of ∼102 A·m-1 with a frequency of ∼104 Hz. The observed experimental characteristics of the effect indicate that its appearance is closely related to the formation of a magnetic standing wave associated to the 180° domain wall movement from the axially magnetized inner core of such wires. The magnitude of the wire's magnetostriction constant plays an essential role as concerns the macroscopic rotation of the wire.
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  • MAGNETIC PROPERTIES AND MAGNETOIMPEDANCE EFFECT IN TM70Cr5Si10Bl5 (TM = Fe, Co, Ni) ALLOYS
    Yong-Kook Kim, Taik-Kee Kim, Heebok Lee, Yoon-Ho Seong, Seong-Cho Yu, ...
    1999 年 23 巻 1_2 号 p. 637-639
    発行日: 1999/01/20
    公開日: 2008/04/17
    DOIhttps://doi.org/10.3379/jmsjmag.23.637
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    Amorphous TM70Cr5Sil0B15 (TM = Fe, Co, Ni) alloys were prepared by rapid quenching technique. Saturation magnetization of the amorphous ribbons was investigated by using SQUID and vibrating sample magnetometer from 5 to 800 K. For these two ferromagnetic alloys, the saturation magnetization up to 0.4 Tc can be described by the Bloch relation, Ms(T) = Ms(0)[1 - BT3/2 - CT5/2]. The spin wave stiffness constants and the range of exchange interaction were analyzed from the magnetization behaviour. And the temperature dependence of the magnetoimpedance effect was investigated in conjecture with their magnetic properties from 10 to 300 K.
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  • Analysis of eddy current loss and magnetization process in Mn-Zn ferrites for power supplies
    S. Yamada, E. Otsuki
    1999 年 23 巻 1_2 号 p. 640-642
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.640
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    Magnetization process in Mn-Zn ferrites has been investigated by analyzing eddy current loss obtained from the relationship between power loss and electrical resistivity. The eddy current loss caused by domain wall displacemen was obtained by subtracting the estimated eddy current loss of uniform magnetization rotation from the experimental eddy current loss. The contribution of the domain wall displacement to the eddy current loss is about 30% at 100kHz and decreases as increasing frequency, followed by vanishing in the frequency range above 600kHz. This result shows that as increasing frequency the magnetic domain is subdivided into smaller size and the uniform magnetization dominates the magnetization process in the high frequency range.
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  • Magnetic microstructure in FePt (001) films with ultrahigh coercivity
    T. Goto, Y. Ide, K. Watanabe, H. Yoshida
    1999 年 23 巻 1_2 号 p. 643-645
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.643
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    Perpendicularly magnetized epitaxial FePt(001) films deposited on MgO (100) substrates have huge coercive forces of 48-54 kOe at room temperature for the thickness below about 300Å. The AFM images show that the films with high coercivity have a granular structure and are mainly composed of small particles below 0.3μm in diameter. The MFM images suggest that each domain contains one particle or some few particles coupled by exchange interactions. So, the domain can behaves as a single-domain. The coercivity depends on the particle size and the degree of epitaxial growth.
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  • Properties of Ion Beam Mixed Co/Pt Multilayered Films
    G. S. Chang, K. H. Chae, C. N. Whang, Y. P. Lee
    1999 年 23 巻 1_2 号 p. 646-648
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.646
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    Ion beam mixing method, which has an advantage in forming a metastable alloy phase, was applied to Co/Pt multilayered films to produce an enhanced magneto-optical(MO) property, and the influence of external magnetic field during ion beam mixing on the property was investigated. Co/Pt multilayered films of [Pt(131Å)/Co(45Å)]× 4 and [Pt(88Å)/Co(88Å)]×4 were prepared onto SiO2 substrates by alternating electron-beam evaporation. Ion beam mixing by 80 keV Ar+ was carried out at varous temperatures with and without external magnetic field. Polar MO Kerr effects were investigated by using Kerr spectroscopy at room temperature. The phase formation and intermixing of ion beam mixed Co/Pt multilayered films were determined using x-ray diffraction and Rutherford backscattering spectroscopy, respectively and showed a correlation with polar MO results.
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  • The Effects of Biquadratic Exchange Coupling and Temperature on Magnetic Properties and GMR in Multilayered Films
    Huang Zhigao, Cai Huang, Lai Hen
    1999 年 23 巻 1_2 号 p. 649-651
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.649
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    Magnetic properties of magnetic multilayers with both the bilinear and biquadratic exchange couplings are investigated phenomenalistically at 0K and finite temperature. It's found that the biquadratic coupling and the number of magnetic layers have a great influence upon the magnetic properties. The complexity of the diagram caused by biquadratic coupling and the temperature effect may explain the variety of hysteresis loops and GMR curves obtained experimentally.
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  • The Phase Diagram and Dynamic Model of Thin Magnetic Film
    Huang Zhigao, Lai Hen, Cai Huang, Zeng Minyong
    1999 年 23 巻 1_2 号 p. 652-654
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.652
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    Based on the located energy minimum, the magnetic states and the lowest energy barriers of two-dimensional magnetic square lattice and sandwiches with long-range dipole-dipole interactions, short-range exchange inter-actions and magnetic surface anisotropy have been calculated. The phase diagram and the transition from perpendicular to in-plane magnetization with varying temperature are presented. We also derive a time dependent decay equations of magnetization and obtain hysteresis at different temperature and measurement time.
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  • Magnetic Properties of Co Particles Alternately Electro-deposited into Micropores of Alumite
    Mitsuru Iida, Liu Ling, Yoshiaki Hata, Shinnichi Kitahata, Eiji Kita
    1999 年 23 巻 1_2 号 p. 655-657
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.655
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    Co fine wires were produced by both AC-electrodeposition (ED) and DC-ED. It was found that the hcp structures with different orientation were realized according to fabrication conditions. The coercive force of 2100 Oe was obtained for DC-ED wires. Co particles were synthesized by the alternating ED of Cu and Co in the pores with using a single electrolyte based on CoSO4 and CuSO4. The deposition voltage was pulse modulated to provide deferent deposition potentials, -1.40 V for Co and -0.65V for Cu. Coercive force ranges between 0 to 1000 Oe and depends on the duration of Co deposition. Superparamagnetism was observed in a case of 1 sec deposition of Co and the length of wires was estimated to be 7 nm.
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  • Magnetic domain structure of micron-size Co line arrays
    Yukio Nozaki, Teruo Ono, Hideki Miyajima, Kimihide Matsuyama
    1999 年 23 巻 1_2 号 p. 658-660
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.658
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    The magnetic domain structure of lithographic Co line (1μm×280μm×70 nm) arrays was investigated in terms of a shape effect. The strong shape anisotropy along the Co line plays an important role in the formation of the magnetic domain structure. The magnetic stray field distribution above the Co line array was measured by using magnetic force microscope (MFM). As the magnetization of the Co line was saturated along the line, the stripe domain structure was observed. The direction of the magnetic moment was periodically modulated along the mean magnetization direction. The periodicity (λ= 0.8μm) is much longer than that of the magnetic ripple structure (∼10 nm) which is generally observed in the polycrystalline ferromagnetic Co thin film. The stripe domain structure is caused by the competition between the crystalline anisotropy perpendicular to the film plane and the shape anisotropy of the line.
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  • Dynamics of Magnetic Domains in Current-Carrying Magnetic Superconductors
    Yoshihisa Enomoto
    1999 年 23 巻 1_2 号 p. 661-663
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.661
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    In magnetic superconductors both superconducting and magnetic ordered phases are known to coexist under certain conditions. A simple phenomenological model is presented to study the dynamics of magnetic domains in such systems when an external current is applied. Qualitative relations between the current-induced dissipative patterns and some physical parameters are discussed numerically on the basis of the model. Especially, a possibility of bistable propagation velocities for a kink front separating both two phases is pointed out, as well as the existence of a stationary localized domain.
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  • Field Characteristics of Axial-Field Motor and 8-pole Impulsed Magnetizing Fixture for the Rotor Magnet using 2-D Model
    Pill-Soo Kim
    1999 年 23 巻 1_2 号 p. 664-666
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.664
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    This paper describes a method for field analysis inside the flat-type brushless DC motor and 8-pole magnetizing fixture for the rotor magnet using 2-D field simulator. Rigorous field analysis of two-kinds entail 3-D analysis. However, this analysis is not often appropriate for system designs because of the time and cost involved. For field analysis in this study, the 3-D problem is reduced to a 2-D boundary value problem by introducing a cylindrical cutting plane at the mean radius of the magnets. Independent of sizes and shapes of systems, a reasonable 2-D field distributions can be obtained.
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  • Self-Organized Magnetic Recording System
    M. Ishihara, H. Mizuseki, K. Ohno, Y. Kawazoe
    1999 年 23 巻 1_2 号 p. 667-669
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.667
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    A new theoretical formulation is proposed on a spin system, which is related to the self-organization of spatially modulated phases and the magnetic multi-valued recording. In this work, macroscopic spin state of the system is determined as a result of a competition between exchange and dipole interactions during the time evolution. Macroscopic patterns are described in linear combinations of periodic functions in Fourier transformed equations with linearized spin interactions. Spins are placed on the lattice points to describe simply this system. Spin configurations can have various symmetrical and asymmetrical patterns even under a uniform external field, according to the balance between interactions. We show that a spatially modulated phase can spontaneously appear by applying just a uniform magnetic field for a finite time interval.
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Chapter 9. Novel Magnetic Phenomena
  • Arrays of Interacting Magnetic Dots and Wires: Static and Dynamic Properties
    B. Hillebrands, S. O. Demokritov, C. Mathieu, S. Riedling, O. Büt ...
    1999 年 23 巻 1_2 号 p. 670-675
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.670
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    Static and dynamic properties of patterned magnetic permalloy films are investigated. In square lattices of circular shaped permalloy dots an anisotropic coupling mechanism has been found, which is identified as being due to intrinsically unsaturated parts of the dots caused by spatial variations of demagnetizing field. In arrays of magnetic wires a quantization of the surface spin wave mode in several dispersionless modes is observed and quantitatively described. For large wavevectors the frequency separation between the modes becomes smaller and the frequencies converge to the dispersion of the dipole-exchange surface mode of a continuous film.
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  • Ferromagnetism in Hubbard models for Quantum Atomic Wires
    M. Ichimura, K. Kusakabe, S. Watanabe, T. Onogi
    1999 年 23 巻 1_2 号 p. 676-678
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.676
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    We have studied the magnetic properties of a certain class of Hubbard models proposed as models for quantum atomic wires with flat single-particle bands. These Hubbard models belong to a class of models to which Mielke-Tasaki theorem for flat-band ferromagnetism can be applied. We also found that the Mielke-Tasaki theorem is applicable in networks of quantum atomic wires. The present findings will be useful for producing flat-band ferromagnetism in quantum atomic wires and two dimensional networks.
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  • Structure and Magnetism of Small Fe Clusters
    A. Taneda, Y. Kawazoe
    1999 年 23 巻 1_2 号 p. 679-681
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.679
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    The ground-state magnetic and electronic properties of small iron clusters are studied by a tight-binding model. In the model, we include the effects of spin-polarization in new tight-binding parameters, which are fitted to reproduce the band-structures calculated by Local Spin Density Approximation (LSDA). The obtained average magnetic moments of iron clusters are larger than the bulk experimental value of 2.21μ B.
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  • Molecular-beam epitaxy of MnAs on patterned GaAs substrates
    Y. Morishita, Y. Sugawara, M. Kato, K. Sato
    1999 年 23 巻 1_2 号 p. 682-684
    発行日: 1999/01/20
    公開日: 2008/01/25
    DOIhttps://doi.org/10.3379/jmsjmag.23.682
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    MnAs were grown on (001) GaAs substrates with mesa-grooves along the [110] and [110] directions having outward sloping sidewalls and inward sloping sidewalls, respectively, by molecular-beam epitaxy with/without the supply of hydrogen radicals (H·). The epilayer shapes have been investigated using secondary electron microscope observations after growth. The vertical film thickness on the (001) surface is irrespective of the rotation of substrates during growth. On the other hand, the lateral film thickness on the sidewall decreased as the Mn flux was decreased. The shapes of MnAs layers were independent on the supply of H·, although the irradiation of H· improves the surface smoothness. These results indicate that the surface-diffusion length of Mn adatoms is small. Consequently, by adjustment of the direction of Mn flux, MnAs layers can be selectively grown on the one side of the sidewalls of patterned substrates.
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