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S. H. Lim, Y. S. Choi, S. H. Han, H. J. Kim, T. Shima, H. Fujimori
1999 Volume 23 Issue 1_2 Pages
537-542
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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The effects of B are investigated on magnetic and magnetostrictive properties of Tb-Fe thin films over a wide B content range up to 5.59 at. %. Intrinsic saturation properties such as saturation magnetization and magnetostriction are found to decrease with increasing B content. The B content dependence of in-plane anisotropy is rather complicated for thin films with a low Tb content where in-plane anisotropy of B-free thin films is weak; in-plane anisotropy deteriorates with a small B addition, but it is enhanced by the addition of a large amount of B. However, anisotropy is little affected by the B addition for thin films with the high Tb fractions where strong in-plane anisotropy already exists without the addition of B. Over the whole composition range examined in this work, the coercive force tends to decrease with increasing B content. A very large magnetostriction of 144 ppm at a magnetic field of 30 Oe, which is largest reported so far in Tb-Fe based thin films, is achieved in a (Tb
0.46Fe
0.54)
94.41B
5.59 thin film.
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S. H. Lim, S. Y. Kang, S. R. Kim, J. K. Park, J. H. Park, Derac Son
1999 Volume 23 Issue 1_2 Pages
543-545
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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Nanocrystalline DyFe
2 melt-spun ribbons with good low field magnetostrictive properties are bonded with a phenol-type binder to form bulk composites. The optimum binder content estimated by considering both magnetostrictive and mechanical properties is about 6 wt. %. A magnetostriction of 202 ppm (at 1.1 kOe), together with a d
max33 value of 0.68 ppm/Oe is achieved in this work.
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Henryk K. Lachowicz
1999 Volume 23 Issue 1_2 Pages
546-548
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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Possible sources of the stress-anneal-induced anisotropy in FINEMET-type magnets are reviewed and discussed resulting in a conclusion that the most probable origin of this anisotropy is the atomic pair directional ordering. It is also evidenced that the anisotropy considered is usually of an easy-plane type.
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H. K. Lachowicz, R. Zuberek, L. Malkinski, T. Kulik
1999 Volume 23 Issue 1_2 Pages
549-551
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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It is shown that gradual devitrification of non-magnetostrictive Co-based metallic glass leads to a giant, five orders of magnitude, increase of its coercivity. This magnetic hardening is due to the pinning by growing fine crystallites much smaller than the domain wall width, the number and size of which increase with an increase of the annealing temperature. It is also shown that FMR-technique is a very sensitive probe of microstructural changes in amorphous magnets.
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D. L. Peng, K. Sumiyama, Z. J. Wang, H. Onodera, K. Suzuki
1999 Volume 23 Issue 1_2 Pages
552-554
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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Perpendicular magnetic anisotropy of Fe-Cr-N nanocrystalline films, prepared by reactive sputtering, have been analyzed by vibrating sample magnetometry, magnetic torque, Mössbauer spectroscopy and ferromagnetic resonance (FMR) measurements. The torque measurement shows that the film has a uniaxial anisotropy whose easy axis lies along the normal to the film plane. The Mössbauer spectra at room temperature (RT) and 4.2 K consist of a broad hyperfine sextet of the α-Fe(Cr) phase and a paramagnetic doublet of the γ'-(Fe, Cr)
4N
x phase. The broad spectrum is attributable to a distribution of the hypefine field. The FMR experiment also shows a broad ferromagnetic absorption peak, resulting from the size and orientation distribution of the fine α-Fe(Cr) grains which have the shape anisotropy.
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M. Ohta, A. Fujita, K. Fukamichi, Y. Obi, H. Fujimori
1999 Volume 23 Issue 1_2 Pages
555-557
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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The relaxation phenomena in the spin-glass state of Y
20(Mn
1-xFe
x)
80 amorphous alloys have been investigated. The single-spin response time τ
0 estimated from the power law between the spin freezing temperatuer T
g and the response time τ increases with increasing x. The concentration dependence of τ
0 is different from that of T
g, therefore, τ
0 is influenced by a short-range order as well as the exchange energy. The average magnetic coupling obtained from the paramagnetic Curie temperature θ
p in Mn-rich regions is antiferro-magnetic, and gradually changes to ferromagnetic with increasing x. It is considered that the ferromagnetic short-range order develops with increasing x, consistent with the theoretical calculation of amorphous Fe.
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K. Miyoshi, G. Ishikawa, K. Saeki, K. Fujiwara, J. Takeuchi
1999 Volume 23 Issue 1_2 Pages
558-560
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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Linear and nonlinear AC susceptibilities are examined for mechanically alloyed amorphous (Fe
1-xRE
x)
0.7Zr
0.3 (
x≤0.4; RE=Ho, Dy and Er) which exhibit spin freezing behaviors due to the random magnetic anisotropy of RE atoms. A negative divergent behavior of nonlinear susceptibility χ
2 is observed for the specimens with
x=0.1, similar to a case of a spin-glass ordering. On the other hand, for the specimens with
x=0.3, χ
2 is found to show an antisymmetric anomaly, indicating a ferromagnetic ordering. Such behaviors reveal a reentrant-spin-glass-like ordering character of the specimens with
x=0.3 at zero DC field. The magnetic phase diagrams are proposed and the ordering characteristics of the systems are discussed with a systematic change of the RE concentration.
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Ikuo Nakai, Makio Kurisu, Shunji Ishio
1999 Volume 23 Issue 1_2 Pages
561-563
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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We present the magnetization sutdy of a melt-spun amorphous alloy Gd
80Si
12B
8 at 4.5 K in magnetic field up to 5.5 T. The ratio of the random magnetic anisotropy constant to the exchange interaction constant is estimated at 0.176. In the intermediate field region the magnetization approaches to saturation as
B-1/2 owing to a weak random magnetic anisotropy where
B is a magnetic field. The random magnetic anisotropy correlates over 1.0 nm, while the ferromagnetic correlation length is 4.1 nm. We discuss the random magnetic anisotropy of Gd
80Si
12B
8 by comparing with other Gd-based amorphous magnets.
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Ikuo Nakai
1999 Volume 23 Issue 1_2 Pages
564-566
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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We report on magnetic properties of an amorphous Gd
22Y
46Cu
32 alloy. The magnetization was measured from 1.7 K to 250 K in the magnetic field up to 12 T. The alloy obeys the Curie-Weiss law above about 80 K with the paramagnetic Curie temperature
Tp=45.6 K. The Arrott plot shows that the system has no spontaneous magnetization even at 1.7 K. The low field magnetization has the hysteresis on temperature in a field-cooled and zero-field-cooled process. These observations suggest that the system is a spin glass with the spin glass temperature
Tg=14.2 K. The high field magnetization follows the spin wave like
T3/2 law below about 8 K. The spin wave stiffness constant thus obtained is
D=2.8 meVÅ which is much smaller than that of an amorphous Gd
68Cu
32 ferromagnet. We discuss the relation between
D and
Tp.
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K. Yamada, K. Shoji, A. Fujita, K. Fukamichi
1999 Volume 23 Issue 1_2 Pages
567-569
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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The spin freezing and random magnetic anisotropy in Tb-Fe-Si amorphous alloys have been investigated. Zero-field and field-cooled magnetizations of (Tb
0.22Fe
0.78)
100-xSi
x (0≤x≤10) amorphous alloys exhibit a magnetic cooling effect. The spin freezing temperature decreases with increasing x. The compensation temperature is lower than the spin freezing temperature. The present amorphous alloys exhibit a negative magnetization because the frozen spins can not be turned over below the compensation temperature.
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Zaychenko S. G., Perov N. S., Gan'shina E. A., Kachalov V. M., Glezer ...
1999 Volume 23 Issue 1_2 Pages
570-571
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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The influence of the low temperature treatment on the physical properties of the Fe- and Co-based amorphous alloys was investigated. The mechanical, magneto-optical and magneto-static parameters of these alloys were measured before and after cooling. Irreversible changes in parameters were found.
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G. Lauhoff, J. Lee, W. Y. Lee, A. Hirohata, A. Samad, J. A. C. Bland, ...
1999 Volume 23 Issue 1_2 Pages
572-574
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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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 ± 0.08μ
B for Co and 0.50 ± 0.04μ
B 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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Y. Yamada, B. Sadeh, C. Lee, M. Doi, M. Matsui
1999 Volume 23 Issue 1_2 Pages
575-577
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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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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N. Nakajima, T. Koide, T. Shidara, H. Miyauchi, H. Fukutani, A. Fujimo ...
1999 Volume 23 Issue 1_2 Pages
578-580
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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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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Yasuhiro Kamada, Hitoshi Kasai, Toshiki Kingetsu, Masahiko Yamamoto
1999 Volume 23 Issue 1_2 Pages
581-583
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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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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Jian-Tao Wang, Zhi-Qiang Li, Yoshiyuki Kawazoe
1999 Volume 23 Issue 1_2 Pages
584-586
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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The structural and magnetic properties of (Cr, Mn, Fe)/Ag monatomic multilayers with the tetragonal
L1
0 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
L1
0 ordered Cr/Ag has an AF1-type antiferromagnetic ground state kith a large local moment 3.30μ
B of Cr, the
L1
0 ordered Mn/Ag has an AF2-type antiferromagnetic ground state with a large local moment 3.63μ
B of Mn, and the
L1
0 ordered Fe/Ag monatomic multilayer has a ferromagnetic ground state with an enhanced moment 2.75μ
B of Fe.
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L. H. Cho, K. S. Yoon, J. I. Lee
1999 Volume 23 Issue 1_2 Pages
587-589
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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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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Q. Sun, Y. Hashi, L. Zhou, Q. Wang, J. Z. Yu, Z. Zeng, Y. Kawazoe
1999 Volume 23 Issue 1_2 Pages
590-592
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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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 Fe
3, Fe
3Rh 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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C. Binns, S. H. Baker, K. W. Edmonds, P. Krüger, J. C. Parlebas, ...
1999 Volume 23 Issue 1_2 Pages
593-595
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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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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Y. Ando, E. Shikoh, T. Miyazaki
1999 Volume 23 Issue 1_2 Pages
596-598
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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Metal halide-based layered perovskites, (RNH
3)
2MCl
4, self-organized organic/inorganic multilayer structure were synthesized, where R is a simple alkylammonium molecule with a long chain length, (CH
3(CH
2)
17) or a
l-methyl-naphthalene (C
10H
9CH
2), M is 3
d transition metal elements. Its layered pcrovskite structure was checked by a FT-IR method. The perovskites of CH
3(CH
2)
17NH
3 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 CuCl
6 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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E. Hirota, R. Nakane, M. Sawamura, S. Chikazumi, K. Mukasa
1999 Volume 23 Issue 1_2 Pages
599-601
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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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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Shin Akutsu, Yoshio Utsushikawa
1999 Volume 23 Issue 1_2 Pages
602-604
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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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 1.6×10
22 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
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Carl E. Patton, Pavel Kabos, Hua Xia, Pavel A. Kolodin, Hong-Yan Zhang ...
1999 Volume 23 Issue 1_2 Pages
605-610
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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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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S. Sugimoto, K. Okayama, H. Ota, M. Kimura, Y. Yoshida, H. Nakamura, D ...
1999 Volume 23 Issue 1_2 Pages
611-613
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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The effect of substitutional elements (Ti, Sc, Zr, Ti
0.5M
0.5, Zr
0.5M
0.5, Sn
0.5M
0.5 (where M = Co, Ni, Zn, Mn, Mg, Cu)) on the natural resonance frequency of Barium M-type hexagonal ferrite (BaFe
12O
19) 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 (H
A) 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 Ti
0.5M
0.5 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 BaFe
9(Ti
0.5Mn
0.5)
3O
19 and BaFe
9.5(Ti
0.5Mn
0.5)
2.5O
19 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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Horst Hoffmann
1999 Volume 23 Issue 1_2 Pages
614-616
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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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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Jin Hanmin, Y. B. Kim, Wang Xue-feng
1999 Volume 23 Issue 1_2 Pages
617-619
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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Hysteresis loops of melt-spun Nd
13Fe
77B
10 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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T. Miyanaga, T. Okazaki, Y. Aono, S. Ikeda, H. Kon
1999 Volume 23 Issue 1_2 Pages
620-622
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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The thermomagnetization curves of Ni
1-xMn
x (
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 Ni
0.79Mn
0.21 and Ni
0.80Mn
0.20 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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T. Okazaki, T. Miyanaga, Y. Kondo, Y. Aono, M. Homma
1999 Volume 23 Issue 1_2 Pages
623-625
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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Ni
3 Mn and Ni
0.77Mn
0.23 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 1
3∼3
3 nm
3 and increases width
S. Minimum cluster size which forms a single domain is about 1
3 nm
3. Magnetism of alloy in which the volume fraction of ordered region is greater than 0.32 (cluster size > 3
3 nm
3), is wholly ferromagnetic.
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N. Perov, A. Vasil'ev, M. Matsumoto, T. Takagi, J. Tani
1999 Volume 23 Issue 1_2 Pages
626-627
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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The magnetic properties of Ni
2+xMn
1-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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N. Perov, A. Radkovskaya, N. Usov, L. Zakharchenko
1999 Volume 23 Issue 1_2 Pages
628-630
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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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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E. E. Shalyguina, N. I. Tsidaeva, L. M. Bekoeva
1999 Volume 23 Issue 1_2 Pages
631-633
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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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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Horia Chiriac, Catalin Sandrino Marinescu, Tibor-Adrian Óv&aacu ...
1999 Volume 23 Issue 1_2 Pages
634-636
Published: January 20, 1999
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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 ∼10
2 A·m
-1 with a frequency of ∼10
4 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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Yong-Kook Kim, Taik-Kee Kim, Heebok Lee, Yoon-Ho Seong, Seong-Cho Yu, ...
1999 Volume 23 Issue 1_2 Pages
637-639
Published: January 20, 1999
Released on J-STAGE: April 17, 2008
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Amorphous TM
70Cr
5Si
l0B
15 (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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S. Yamada, E. Otsuki
1999 Volume 23 Issue 1_2 Pages
640-642
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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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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T. Goto, Y. Ide, K. Watanabe, H. Yoshida
1999 Volume 23 Issue 1_2 Pages
643-645
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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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 0.3μ
m 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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G. S. Chang, K. H. Chae, C. N. Whang, Y. P. Lee
1999 Volume 23 Issue 1_2 Pages
646-648
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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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 SiO
2 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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Huang Zhigao, Cai Huang, Lai Hen
1999 Volume 23 Issue 1_2 Pages
649-651
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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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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Huang Zhigao, Lai Hen, Cai Huang, Zeng Minyong
1999 Volume 23 Issue 1_2 Pages
652-654
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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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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Mitsuru Iida, Liu Ling, Yoshiaki Hata, Shinnichi Kitahata, Eiji Kita
1999 Volume 23 Issue 1_2 Pages
655-657
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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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 CoSO
4 and CuSO
4. 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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Yukio Nozaki, Teruo Ono, Hideki Miyajima, Kimihide Matsuyama
1999 Volume 23 Issue 1_2 Pages
658-660
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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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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Yoshihisa Enomoto
1999 Volume 23 Issue 1_2 Pages
661-663
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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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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Pill-Soo Kim
1999 Volume 23 Issue 1_2 Pages
664-666
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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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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M. Ishihara, H. Mizuseki, K. Ohno, Y. Kawazoe
1999 Volume 23 Issue 1_2 Pages
667-669
Published: January 20, 1999
Released on J-STAGE: January 25, 2008
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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
