Journal of the Magnetics Society of Japan
Online ISSN : 1880-4004
Print ISSN : 0285-0192
ISSN-L : 0285-0192
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Volume 13, Issue 2
Displaying 1-50 of 96 articles from this issue
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Magnetic Recording Media
  • Recording Characteristics and Durability of Fe-Co-O/Fe-Co Double-Layered Perpendicular Magnetic Recording Medium
    M. Isurugi, S. Nasu, K. Matsumoto, A. Nakajima, K. Saiki
    1989 Volume 13 Issue 2 Pages 71-76
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.71
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    In order to enhance perpendicular magnetic recording characteristics of an Fe-Co-O medium with a large perpendicular anisotropy, an Fe-Co underlayer with a coercive force of about 100 Oe has been investigated. The reproduced voltage of the Fe-Co-O/Fe-Co double-layered medium with the most suitable film thickness is five times as large as that of the single-layered medium. However, the Fe-Co-O/Ni-Fe double-layered medium whose underlayer has higher permeability did not show such great improvement in reproduced voltage. These results suggest that the effect of the Fe-Co underlayer is different from the decrease of demagnetization field caused by the Ni-Fe layer in the Co-Cr/Ni-Fe double-layered medium. It has also been clarified that the Fe-Co-O/Fe-Co double-layered flexible disk has high wear resistance of more than 10 million passes without a protection layer because of the higher stiffness and stronger adhesive force existing between the Fe-Co layer and polyimide substrate.
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  • Relationship between Head/Tape Contact Condition and Tape Stiffness
    H. Uenaka, H. Mukae, A. Kuroe, M. Mikoda
    1989 Volume 13 Issue 2 Pages 77-80
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.77
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    An experimental study on tribology in head/tape interface has been carried out in order to develop high performance video tapes. In this paper, we report a system for measuring directly the head contact force, and the relationship between contact conditions and tape stiffness. The video head has been found to have the contact force of about 20-30 mN, and its distribution for rotation angle of cylinder is approximately expressed by exponential functions in the steady state. Under low stiffness conditions, the distribution falls into disorder, and a reproduced signal is degraded. It is thus very important to maintain a suitable stiffness to obtain a stable contact state in the head/tape interface.
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  • Non-Destructive Detection of Drop Out by a Measurement of Tape/Head Contact Condition
    H. Mukae, M. Mikoda, A. Kuroe, K. Tahara
    1989 Volume 13 Issue 2 Pages 81-84
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.81
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    With the recent increase in recording density of VTR, tape/head interface problems become more important. Magnetic recording characteristics such as drop out are greatly affected by dust and protrusion on tape. In this paper. we report on non-destructive detection of drop out using a system which measures tape/head contact condition. It has been experimentally found that the stretch of tape/head spacing was several hundred times with the height of protrusion, and that the coefficient of record/play back spacing loss was 100 dB.
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  • Film Composition and Perpendicular Magnetic Anisotropy of Electroless-Plated CoNiReP Films
    T. Osaka, T. Homma, K. Inoue, Y. Yamazaki, T. Namikawa
    1989 Volume 13 Issue 2 Pages 85-88
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.85
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    Magnetic properties and microstructure of electroless-plated CoNiReP films varying primarily in cobalt content were investigated to clarify the origin of their magnetic anisotropy. The films which show perpendicular magnetic anisotropy contain ca. 25-40% of cobalt in deposit. They also show higher crystallinity and a c-axis orientation of hcp cobalt. It is considered that the anisotropy of the films is mainly due to the crystalline anisotropy based on this crystallographic structure, and that the smaller Ms value which decreases the demagnetizing field enhances the anisotropy. The shape anisotropy caused by segregation of the films is also considered to affect the overall anisotropy.
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  • Pseudo Output and Magnetic Properties of Fe-Al-Si Film in MIG Head
    A. Gyotoku, H. Tomiyasu, N. Koga, F. Kobayashi
    1989 Volume 13 Issue 2 Pages 89-94
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.89
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    Fe-AI-Si film has a layer with inferior magnetic properties near the boundary between the film and a ferrite core. This layer, which acts as a pseudo gap in MIG heads, is caused by nonuniform structure of the Fe-AI-Si film and the diffusion between the film and ferrite. Improvement of the properties of the Fe-Al-Si film requires better crystalline orientation, smaller grain size and homogeneous film structure, which is attained by selecting optimized substrates. When the MIG head uses a single-crystalline ferrite preparing (110) plane as a gap surface, the head has no pseudo output as does a MIG head of poly-crystalline ferrite with Fe-Ni/Fe-Al-Si double layer film, because both MIG heads have good crystalline orientation and homogeneous film structure.
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  • Inductance and Read-Write Characteristics for Thin Film Heads
    K. Mitsuoka, T. Iwakura, T. Kobayashi, H. Fukui, S. Narishige, Y. Sugi ...
    1989 Volume 13 Issue 2 Pages 95-98
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.95
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    The inductance and read-write characteristics for thin film heads with various magnetostriction constants were investigated. Heads with a combination of positive magnetostriction constants for top yoke and negative magnetostriction constants for bottom yoke exhibited excellent read-write characteristics. Such a result could be explained by the increase of the difference between the inductance at zero bias and magnetized cores, that is, permeability in cores. High permeability was caused by the magnetoelastic effect based on the induced uniaxial stresses of permalloy films. In addition, overwrite characteristics became excellent as values of the bias magnetomotive force obtained from the inductance characteristics increased. It was concluded that the measurement of the inductance characteristics is a very powerful method of evaluating magnetic tips.
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  • Effect of Yoke Pattern on Recording Characteristics of Thin Film Heads
    K. Yamagata, N. Miyamoto, H. Fukui, S. Narishige, Y. Sugita
    1989 Volume 13 Issue 2 Pages 99-102
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.99
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    The dependence of the magnetic anisotropy of the thin film heads on the side angle of the yoke was studied. Because of the increase of yoke reluctance, it had been thought that the reproducing sensitivity decreases with the increase of side angle. However, measurement revealed that the reproducing sensitivity increases with the side angle. To determine the reason for this sensitivity increase, the stress and the stress induced anisotropy were calculated threedimensionally. According to these analyses the magnitude of the tensile stress along the hard axis increased with the side angle, and therefore the anisotropy field decreased when the heads had a positive magnetostriction constant. Decrease of the anisotropy field was confirmed by observations using the magneto-optic Kerr effect. It is thus concluded that the side angle affects the magnitude of the magnetic anisotropy, in addition to the yoke reluctance and the domain structure.
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  • Three Dimensional Stress and Magnetic Anisotropy Analyses for Thin Film Heads
    H. Koyanagi, R. Arai, K. Mitsuoka, H. Fukui, S. Narishige, Y. Sugita
    1989 Volume 13 Issue 2 Pages 103-108
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.103
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    Stress was calculated using the three dimensional finite element method. There are two kinds of stress, thermal and intrinsic. Intrinsic stress was equivalently treated as a thermal stress using modified thermal expansion coefficients. Modified values of films were selected to fit the calculated displacements to the measured ones for circular substrates with a deposited layer. The accuracy of calculations was within 20% of measurements, and the stress distribution around the backgap qualitatively corresponded to the domain structure observed by spinpolarized SEM. It was found that the tensile stress along the hard axis was dominant in the pole tip region. The dependence of magnetic anisotropy on magnetostriction constants was calculated using the obtained stress. Suitable magnetostriction constants for bottom yoke were found to be smaller than those for top yoke.
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  • Three Dimensional Analytical Head Field Model of a Perpendicular Recording Head
    K. Okuda
    1989 Volume 13 Issue 2 Pages 109-112
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.109
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    We previously described a simple, analytical, 3 dimensional head field model for a perpendicular recording head with a soft magnetic underlayer. In that model, we assumed two magnetically charged planes to obtain the head field at the region close to the head surface and under the pole tip. For simplicity of calculation, the charge distribution was approximated by a step function. However, it was found that the field can be analytically obtained from the a+1/(b-cx2) type of charge distribution more accurately than from a step function approximation. In this paper, the derivation of the modified method is explained, and the head fields obtained by the modified model are compared with those of the previous model and large-scale experimental results. The modified model gives smoother head fields and better agreement with large-scale experimental results than the previous model.
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  • Recording and Reproducing Efficiency of Main-Pole Driven Perpendicular Magnetic Head
    S. Yamamoto, Y. Nakamura, S. Iwasaki
    1989 Volume 13 Issue 2 Pages 113-116
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.113
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    The reproducing efficiency of a perpendicular magnetic recording head was investigated. To improve the reproducing efficiency, scaling down and designing the head structure with a closed magnetic circuit and a coil wounl close to the main-pole are very effective. We have designed and fabricated a main-pole driven type perpendicular head with a thin-film coil wound around the main-pole film in addition to the wire coil. The reproduced voltage per turn of the thin-film coil was confirmed to be double that of the wire coil, and the same reproduced voltage as that of the thin-film perpendicular head with double-sided return path core can be obtained when the two coils of this head are used in series.
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  • Characteristics of Parametric Reproducing Head for Perpendicular Magnetic Recording
    Y. Tanno, T. Yamakoshi
    1989 Volume 13 Issue 2 Pages 117-120
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.117
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    A magnetic reproducing head using parametric oscillation has been developed for perpendicular magnetic recording. The head is based on parametric oscillation in a resonant circuit comprised of a single pole type perpendicular magnetic recording head and four varactor diodes for time variable capacitance. In this paper, the reproducing principle and experimental results are described. The characteristics of the output voltage are independent of signal frequency from DC to 3 MHz. The output voltage is proportional to input signal up to 1 V.
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  • Side Crosstalk Response in Perpendicular Magnetic Recording with Narrow Track Width Single-pole Head
    J. Numazawa, Y. Yoneda, F. Aruga, T. Horiuchi
    1989 Volume 13 Issue 2 Pages 121-124
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.121
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    Off-track side crosstalk response and Bitter pattern on a perpendicular magnetic recording medium observed after recording with a single-pole head were investigated experimentally for various track widths and bit lengths. A Co-Cr/permalloy flexible disk medium of 3.5″ diameter and single-sided single-pole heads of 3.8μm, 5.5μm, 7.0μm track width were used for the evaluation. The following results were obtained by this experiment: 1) the recorded track width accurately coincided with the width of a main pole even for the very narrow track width of 3.8μm; and 2) side crosstalk in perpendicular magnetic recording is determined by the side reading behavior of the single-pole head used.
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  • Magneto-Optical Observation of Magnetic Domains in Rubbing Surface of a Ferrite Head
    M. Kaneko, K. Aso
    1989 Volume 13 Issue 2 Pages 125-128
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.125
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    A magneto-optical microscope was used to observe in-plane magnetic domains. The magnetic contrast caused by the longitudinal Kerr rotation was optimized by adjusting an analyzer and a phase compensator. The contrast in the raw image detected by a CCD video camera was much improved by an image processor. Closure domains were clearly observed in both single layered and double layered permalloy thin square films. The magnetic domain wall was found to be Neel wall like. The observation revealed that the multidomain state is still stable in a 3μm wide double layered permalloy film. Magnetic domains in rubbing surface of a ferrite head were successfully observed for the first time. The magnetization reversal was expanded from near the head gap with re-producibility, when a coil current was increased in a direction opposite to the previous saturation current. A magnetization model was proposed to explain apparent hysteresis.
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Magnetic Recording Characteristics
  • Recording Characteristics on Pulse Train Write Current Waveform
    S. Fuchigami, K. Matsui, H. Sakata
    1989 Volume 13 Issue 2 Pages 129-132
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.129
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    A magnetic recording head using separated read and write elements can reduce the number of write coil turns. Therefore, the write element construction can be made simply on this type of thin film head. However a large current is required and heat is generated when a square-wave write current waveform is used due to fewer coil turns. A pulse train write current waveform is one solution to this problem this reduces heat generation, cross feed and power dissipation. We discuss the possibility of high density magnetic recording using a pulse train recording. A two-turn coil write head and MR read head were used for the experiment. We found no significant difference of write-read characteristics from a conventional square-wave NRZI write current waveform. Double density NRZI pulse train recording best minimized the bit error rate, and a recording density more than double that for NRZI was attainable.
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  • Theoretical Study of the Characteristics of Modulation Noise in Magnetic Tapes
    A. Kuroe, M. Mizoh, M. Mikoda
    1989 Volume 13 Issue 2 Pages 133-136
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.133
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    The influence of surface roughness on modulation noise was studied theoretically using a simplified sinusoidal head-tape contact model. Co-γFe2O3 tapes having sinusoidal surface roughness were prepared, and their modulation noise was measured by VHS VTR. It was found that the modulation noise contained both amplitude modulation (AM) and phase modulation (PM) components; AM and PM noise increased with the increase in ratio of surface roughness to recording wavelength, and PM noise increased with the decrease in ratio of spatial wavelength of tape surface to recording wavelength.
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  • A Study on Recorded Transitions in Particulate Perpendicular Recording Media
    K. Sueoka, K. Abkemeier, K.G. Ashar
    1989 Volume 13 Issue 2 Pages 137-140
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.137
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    The shapes of recoeded transitions in a perpendicular recording medium were studied experimentally. using a large-scale model consisting of a single pole head and a particulate recording layer with an underlayer. Magnetization distributions were obtained from the measured magnetic field distributions at the medium surface. The results show that the shapes of the transitions strongly depend on the write current values and the initial erasing conditions. The optimum write current for the large-scale medium corresponds to the value that generates a field 2.6 times larger than the coercivity at the center of the medium.
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  • Approximate Analysis of Perpendicular Magnetic Recording Characteristics
    K. Nishimura, Y. Nakamura, S. Iwasaki
    1989 Volume 13 Issue 2 Pages 141-144
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.141
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    In perpendicular magnetic recording using a single pole type magnetic head and a double-layered medium, a sharp magnetization transition is formed in the Co-Cr layer of the medium because the demagnetizing field rarely arises in the region of magnetization transition. Therefore, the shapes of isolated pulses can be easily calculated by a head field and a M-H loop of the medium. In this paper, a simple mean of approximation for the analysis of an isolated pulse shape in perpendicular magnetic recording is described. For the analysis, the distribution of the head field is computed by FEM considering the head-to-medium magnetic interaction, and an actual M-H loop are used. The calculated narrow pulse width in perpendicular magnetic recording is compared with those measured and calculated in longitudinal magnetic recording.
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  • Analysis of Head to Medium Magnetic Interaction in Perpendicular Magnetic Recording by Finite Element Method Combined with Magnetization Model
    I. Tagawa, Y. Nakamura
    1989 Volume 13 Issue 2 Pages 145-148
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.145
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    A new simulation program has been developed for the analysis of perpendicular magnetic recording. This is the finite element method program which adopts a magnetization curling mode and a statistical method to calculate vectorial magnetizations in a medium. Using this simulation analysis, we could explain quantitatively the effects of the magnetic interaction between a single-pole head and a doublelayer medium which were predicted from the experimental results. Furthermore, we were able to analyze a vectorial recording and reproducing mechanism. This new program is a very powerful tool which can more precisely simulate the magnetic recording process.
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  • Behavior of Soft Magnetic Backlayer in Recording and Reproducing Process On Perpendicular Magnetic Recording Media
    S. Tadokoro, K. Ouchi, Y. Nakamura, S. Iwasaki
    1989 Volume 13 Issue 2 Pages 149-152
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.149
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    Double layered Co-Cr perpendicular recording media were studied with respect to effect of a Ti thin intermediate layer between the Co-Cr and Ni-Fe layers on recording and reproducing characteristics. The increase of the output voltage by introduction of the Ti layer was explained by the increase of the effective permeability of the total system of the perpendicular head and the back layer of the D.L. medium. It was found that the highly permeable back layer achieved by using the Ti layer induces a broadened waveform and an increase of peakshift of reproduced pulses.
    We concluded that media without a Ti layer are superior to those with a Ti layer with respect to the recording resolution.
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  • Recording Characteristics of Electroless-plated CoNiReP/NiWP Double Layers
    H. Matsubara, S. Mitamura, K. Noda, T. Osaka, F. Goto
    1989 Volume 13 Issue 2 Pages 153-156
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.153
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    Electroless-plated CoNiReP/NiWP double layer films were investigated for perpendicular magnetic recording media as flexible disks. The magnetic properties of CoNiReP recording layer, such as a saturation magnetization (Ms) value and squareness ratio of perpendicular hysteresis loops (SQR(⊥)). were changed by Ni WP underlayers. The reproduced output voltage of CoNiReP/NiWP flexible disks at low recording density with a ring-type head increased with Ms values of recording layer and underlayer. Moreover. the D50 value of 172 kFRPI was attained by the highest SQR(⊥) medium of the double layer evaluated with a 0.20μm gap length sendust ring-type head. This may be mainly due to large perpendicular anisotropy of the top region of recording layer which is improved by the underlayer addition.
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Magneto-Optics
  • Cotton-Mouton Spectrum in Cobalt-Substituted Magnetic Garnet
    K. Sato, Y. Aman, K. Tamanoi, T. Saito, K. Shinagawa, T. Tsushima
    1989 Volume 13 Issue 2 Pages 157-162
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.157
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    Spectra of the Cotton-Mouton effect and the Faraday rotation were measured in cobalt-substituted magnetic garnet films between 0.5 and 2.0μm using a piezobirefringent modulator. The experimental spectra were compared with those obtained by theoretical analysis in the framework of the ligand-field theory. A satisfactory agreement was obtained between experiment and theory with a reasonable set of fitting parameters.
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  • Sputter Deposition of Ce-Substituted Iron Garnet Films with Giant Magneto-Optical Effect
    M. Gomi, K. Satoh, H. Furuyama, M. Abe
    1989 Volume 13 Issue 2 Pages 163-166
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.163
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    Epitaxial monocrystalline and polycrystalline films of highly Ce-substituted YIG have been prepared by rf-diode sputtering. The threshold temperature for epitaxial growth increased with Ce content at a rate of 80°C/Ce ion from 390°C of YIG film. The epitaxy was achieved for Ce content up to 1.5 per formula unit. The Ce-substitution induced exceptionally large Faraday rotation in the visible and near infrared regions, the factor per Ce ion being 2×104 deg/cm at λ=633 nm and -1.3×104 deg/cm at 1150 nm. The polycrystalline films were obtained in single garnet phase for Ce content up to 0.7. They were fully crystallized when post-annealed above 775°C. The films were quite homogeneous and grain boundaries were indiscernible. Thus. Ce : YIG films are a very promising magneto-optical material.
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  • A New Measurement System of the Surface Magneto-Optic Kerr Effect (SMOKE)
    Y. Suzuki, M. Ohhiraki, H. Kikuchi, T. Katayama, N. Koshizuka
    1989 Volume 13 Issue 2 Pages 167-170
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.167
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    A new measurement system of surface magnetooptic Kerr effect (SMOKE) has been developed. Combination of a polarization modulating method using electric detection and signal processing using a computer system provides very high sensitivity, 10-4 degrees, and a good signal to noise ratio. Moreover, electrical calibration using a Faraday cell makes it possible to measure the absolute value of a Kerr rotation angle of the order of 10-4 degrees. SMOKE hysteresis of 2-atomic layer of fcc-Co grown on a Cu(100) surface is successfully measured and its Kerr rotation angle is about 5×10-4 degrees.
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  • Temperature Dependence of Faraday Effect for Cd1-xMnxTe Films
    T. Koyanagi, K. Yamano, T. Sota, K. Matsubara
    1989 Volume 13 Issue 2 Pages 171-174
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.171
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    A theoretical treatment of the Faraday effect has been made with respect to Cd1-xMnxTe films prepared by ionized-cluster beams. The Faraday rotation spectra are calculated taking account of a broadening parameter Γ of exciton absorption in a nondegenerate second order perturbation theory. The calculated spectra are compared with the experimental data of Cd1-xMnxTe films. The results reveal that the thermal broadening of exciton absorption is due to the scattering of an exciton by longitudinal optical (LO) phonons.
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  • Effects of an Electric Field on the Faraday Rotation of Cd1-xMnxTe Films Prepared by the Ionized-Cluster Beam Technique
    K. Yamano, T. Sota, T. Koyanagi, K. Nakamura, K. Matsubara
    1989 Volume 13 Issue 2 Pages 175-178
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.175
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    Pronounced effects of an electric field on the Faraday rotation of Cd1-xMnxTe films prepared by ionized-cluster beam technique have been investigated in the wavelength region from 800 nm to 480 nm at room temperature. With an increase in an electric field applied to the film plane, a marked shift in dispersion frequency toward a longer wavelength region is observed in Faraday rotation spectra of the Cd1-xMnxTe film, and its peak height decreases. The electric field-induced change of peak height at the dispersion frequency is of the order of 10-4 deg./cmG per one kV/cm, and enlarges with increase in composition x. This can be explained by the ionization of excitons due to the Franz-Keldysh effect.
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  • On the Enhancement of the Magneto-Optical Kerr Rotation for PtMnSb by Annealing
    K. Takanashi, H. Fujimori, J. Watanabe, M. Shoji, A. Nagai
    1989 Volume 13 Issue 2 Pages 179-182
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.179
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    The magneto-optical Kerr rotation angle θK for polished bulk PtMnSb was found to show a great enhancement after annealing at temperatures higher than 400°C, although the change in the spectrum of reflectance R was very small. X-ray photoelectron spectroscopy analysis and the calculation of R and θK assuming the formation of overlayer revealed that the enhancement of θK was not attributable to the overlayer effect. It was found that the enhancement of θK was rather correlated with the change of magnetic anisotropy at the surface by annealing.
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  • Magneto-Optical Spectra in Single Crystals of Cr-Te Compounds
    Y. Aman, M. Hirai, M. Murayama, K. Sato
    1989 Volume 13 Issue 2 Pages 183-186
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.183
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    Optical and magneto-optical properties of single crystals of Cr2Te3 and Cr3Te4 grown by chemical vapor transport technique were studied. Spectra of normal incidence reflectivity were measured at room temperature on both samples. On Cr3Te4, magnetooptical spectra were also measured. Spectra of the diagonal and off-diagonal elements of the conductivity tensor were obtained from the measured spectra. These were compared with those estimated from density of state curves calculated by Dijkstra and showed appreciable agreement. From these results it is concluded that transitions from Cr3d to C. B. for majority spins and Te5p to Cr3d for minority spins are responsible for the observed optical absorption and magneto-optical effects.
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  • Stress Induced Magnetic Anisotropy of YBi2Fe5-xGaxO12 Sputtered Films
    Y. Kigami, T. Namikawa, Y. Yamazaki
    1989 Volume 13 Issue 2 Pages 187-190
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.187
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    In order to study the origin of perpendicular magnetic anisotropy in Bi-substituted iron garnet thin films, a series of samples with the composition of YBi2Fe5-xGaxO12 (0.36<x<0.97) was prepared by rf sputtering onto several substrates having various thermal expansion coefficients. The stress (σ) was calculated from the difference in thermal expansion between the film and the substrate. The anisotropy constant (Ku) of the films increased linearly with a in the range from σ=-9.0 × 109 erg/cm3 to 3.0 × 109 erg/cm3. Ku decreased linearly with x in the composition range. The experimental results were discussed and compared with the results on Al substituted films.
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Magneto-Optical Recording
  • Amorphous Fiber Core Head with Low Power Dissipation for Magnetic Field Modulation on Magneto-Optic Recording
    T. Nagaki
    1989 Volume 13 Issue 2 Pages 191-194
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.191
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    CoFeSiB system soft magnetic amorphous fiber of about 10μm diameter as drawn (AMFD) has a unique B-H loop at the MHz region. We clarified that if the AMFD core is used at about 1 kGauss at 1 MHz, the core loss is extremely low (1.7 J/m3), although the permeability is small (200).
    We designed and fabricated a magnetic head to use in the AMFD core for magneto-optic recording by magnetic field modulation with an AMFD center core 1 mm in diameter.
    Comparison of the AMFD core head and a conventional Ferrite head shows that the loss of the former is about 60% of the latter under the same conditions of magnetic field and inductance.
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  • A Magneto-Optical Disk for Readout Using Circular Dichroism Effect
    Y. Murakami, Y. Nakata, H. Katayama, A. Takahashi, K. Ohta, T. Ishikaw ...
    1989 Volume 13 Issue 2 Pages 195-198
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.195
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    A magneto-optical (M-O) disk for readout using the circular dichroism effect was investigated. With this method, the optical head can be simplified because recorded bits are directly detected as the intensity change of reflected light. We studied multi-layer structure films in order to enhance the circular dichroism effect and found a preferable quadrilayer structure M-O medium consisting of AlN, GdTbFe, AlN and Al. The read-out signal quality was evaluated with the optical head and we achieved a 45 dB carrier-to-noise ratio at 1.3μm bit length.
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  • Numerical Analysis of Magnetization Reversal in TbCo Magneto-Optical Recording Disks
    S. Ashida, Y. Mizusawa, H. Nagatani, A. Tsutai, K. Ichihara
    1989 Volume 13 Issue 2 Pages 199-202
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.199
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    Thermo-magnetically reversed domain size in TbCo magneto-optical disks has been numerically analyzed. The recorded domain radii were derived from the calculation of partial differentials of magnetic energies at the domain walls according to Huth's model. Disk samples were prepared and the measured thermo-magnetic properties were used for the calculation. The relative value of the domain wall energy was obtained using the mean field theory, and its absolute value was set so that the calculated and measured threshold recording powers were identical to each other. The recorded domains in the disks were observed with an Ar laser scanning polarization microscope to compare their radii with the calculated ones. This numerical analysis yielded fairly good estimations in the rather high power region, whereas the calculated radii were much smaller than the measured ones near threshold recording power.
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  • Perpendicular Magnetic Anisotropy of TbFe, TbFeCo, and Dy-Fe Compositionally Modulated Films
    F. Tsuneda, S. Nishimura, S. Honda, T. Kusuda
    1989 Volume 13 Issue 2 Pages 203-208
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.203
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    Compositionally modulated TbFe and TbFeCo amorphous films were prepared on glass substrates by means of the bias modulated sputtering method. The modulated structure was confirmed for the modulation length larger than 14Å by X-ray small angle diffraction. Also, sharp layer-boundaries were clearly observed by the cross-sectional TEM method. The magnetic perpendicular anisotropy energy Ku increases with decreasing modulation length Λ, because of the interface anisotropy Ks which arises from the anisotropic ordering of Tb-Fe atom pairs or the internal stress at the layer-boundaries. Dy-Fe multilayered films prepared by a vacuum evaporation technique were also investigated. As the periodic length Λ decreases, both the saturation magnetization Ms and the Kerr rotation angle θK decrease steeply at Λ nearly euals 40Å, because of the change in Fecrystal structure from bcc to fcc or amorphous. The perpendicular anisotropy Ku increases proportionally to 1/Λ with the interface anisotropy Ks=0.8 erg/cm2 and Ks=1.24 erg/cm2 for R. T. and 80 K, respectively.
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Hard Magnetic Materials
  • Magnetic Aftereffect Constant of Nd-Fe-B Sintered Magnet
    H. Nishio
    1989 Volume 13 Issue 2 Pages 209-212
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.209
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    The magnetic field and temperature dependences of the magnetic aftereffect constant Sv were measured for Nd-Fe-B sintered magnet on a J-H demagnetizing curve in the practical temperature range for a permanent magnet between 293 and 400 K. Sv is constant and independent of the magnetic field in the range from the point near (BH)max to the demagnetizing field whose magnetization J was -0.7 T. Sv decreased linearly as temperature increased. The value of Sv and temperatre dependence of Sv for Nd-Fe-B sintered magnet were considerably larger than those of Sm2Co17 sintered magnet.
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  • Magnetic Properties of Cast and Hot-pressed Pr-Fe-B Magnets
    O. Kobayashi, T. Yamagami, K. Akioka, T. Shimoda
    1989 Volume 13 Issue 2 Pages 213-218
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.213
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    A new process has been developed to produce high energy bulk Pr-Fe-B magnets without the handling of any magnetic powder or powder-like ribbons. This process consists of three main steps: casting, hot-pressing and annealing, and minimizes the oxygen contamination of magnets. A typical composition of cast alloy is Pr17Fe76.5B5Cu1.5. Using this type of alloy, crystal alignment along the c axis is easily introduced by hot-pressing. Copper plays two important roles in this process: high coercivity and excellent magnetic alignment are achieved simultaneously by its addition. The magnetic properties of hotpressed Pr17Fe76.5B5Cu1.5 magnets are: Br=12.5 kG, iHc = 10.0 kOe and (BH)max=36.2 MGOe. The cast alloy of this composition also has an iHc of 7.3 kOe and a (BH)max of 9.2 MGOe after annealing at 1000°C for 24 hours. The steep rise in the initial magnetization curve indicates a nucleation controlled coercivity mechanism.
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  • Magnetic Properties of Melt-Spun Nd-Fe-Co-B-V Alloys and Their Bonded Magnets.
    H. Yamamoto, M. Nagakura, Y. Ozawa, T. Katsuno
    1989 Volume 13 Issue 2 Pages 219-222
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.219
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    Melt-spun ribbons of Nd-Fe-Co-B-V alloys were prepared by the single roller rapid-quenching method, and the effects of V substitution and substrate surface velocity on the magnetic properties were studied. The magnetic properties of their isotropic bonded magnets made of optimumlyquenched ribbons were also measured. A maximum energy product of 152.7 kJ/m3 was obtained with Nd11Fe72Co8B7.5V1.5 alloy ribbon prepared at a substrate surface velocity of 17.1 m/s. The magnetic properties of these high quality ribbons are isotropic. The maximum energy product obtained in these bonded magnets of Nd11Fe72Co8B7.5V1.5 alloy was 92.8 kJ/m3.
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  • Magnetic Properties of Rapidly Quenched (Fe1-xCox)17Sm2 Alloys
    T. Miyazaki, M. Takahashi, M. Takahashi
    1989 Volume 13 Issue 2 Pages 223-226
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.223
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    The formation of metastable TbCu7-type disordered compounds and their magnetic properties for rapidly quenched (Fe1-xCox)17Sm2 (0 ≤ x ≤ 1.0) alloys were investigated by X-ray diffraction and thermomagnetization analysis. The disordered compound is formed with single phase in the range 0.5 ≤ x ≤ 1.0 at the disk velocity of 42 m/s. The disordered phase is magnetically harder than the ordered phase of Th2Zn17 structure.
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Soft Magnetic Materials
  • Magnetostriction Measurements for Amorphous Wires
    Y. Konno, K. Mohri, S. Uchiyama
    1989 Volume 13 Issue 2 Pages 227-230
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.227
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    Measurements of the saturation magnetostriction constant λs have been difficult for amorphous wires using conventional techniques due to their very thin form (125-10μm diameter). In this paper, magnetostriction measurements for these wires are stably carried out using a magnetization rotation model and applying a compressive stress to positive magnetostriction wires and a tensile stress to negative magnetostriction wires. The value of λs of 35 ppm was obtained for an as-prepared Fe77.5Si7.5B15 wire at room temperature.
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  • Magnetic Properties of Ultrafine Crystalline (Fe-Cu1-Nb3)-Si-B Quasi-ternary Alloys and Improvement of Their Magnetic Properties by Magnetic Field Annealing
    Y. Yoshizawa, K. Yamauchi
    1989 Volume 13 Issue 2 Pages 231-236
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.231
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    The influence of Si, B contents and magnetic field annealing on magnetic properties of ultrafine crystalline (Fe-Cu1-Nb3)-Si-B quasi-ternary alloys have been studied. The alloy containing 13.5 at%Si and 9 at%B shows the most excellent soft magnetic properties. In this alloy, the relative permeability at 1 kHz is about 1×105. On the other hand, the alloys containing about 2 at%Si and 13 at%B show a high flux density of about 1.55 T and those containing about 17 at%Si and 5 at%B show nearly zero magnetostriction. Magnetic field annealing is very effective to improve hysteresis curves of these alloys for many applications.
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  • Magnetic Properties and Magnetoresistance Effect in Evaporated NiFeCo Films
    T. Tatsumi, K. Yamada, Y. Motomura, H. Urai
    1989 Volume 13 Issue 2 Pages 237-240
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.237
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    The anisotropic magnetoresistance (MR) ratio and magnetic anisotropy field HK have been examined for (Ni0.82Fe0.18)100-x Cox and Ni82Fe18-xCox evaporated films and those annealed at 320°C for 2 hours, to evaluate their usefulness as MR head materials. For the (Ni0.82Fe0.18)100-x Cox films, MR ratio is almost constant regardless of change in Co concentration. For the Ni82Fe18-xCox films, MR ratio increases as the Co concentration increases. Furthermore, MR ratio after the annealing raises to 5% in the Co concentration range greater than 6 wt%. HK increases as the Co concentration increases, and is not changed by the annealing. The increase in MR ratio by the annealing for the Ni82Fe18-xCox films is related to inhomogeneous strain and lattice defects. For Ni82Fe12Co6 film, 5.1% MR ratio and 7.8Oe HK were obtained. These values seem appropriate for application to MR heads.
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  • Soft Magnetic Properties of Fe-Co/ZnO Multilayer Films
    T. Miyazaki, F. Sato, M. Takahashi, T. Tanaka, T. Shimazu
    1989 Volume 13 Issue 2 Pages 241-244
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.241
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    The dependence of soft magnetic properties on the thickness and composition has been investigated for sputtered Fe-Co/ZnO multilayers. The coercivity decreases with the decrease in average size of crystallites D, in particular from 9 to 17 nm for all multilayers except Co/ZnO. Magnetic properties with Hc=160 A/m and μe(10 MHz)=800 are obtained for Fe/ZnO and 24Co-Fe/ZnO multilayers with D=2∼3 nm.
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Magnetism
  • Magnetic Properties of Magnetic Fluids near Melting Point
    N. Inaba, H. Miyajima, S. Taketomi, S. Chikazumi
    1989 Volume 13 Issue 2 Pages 245-248
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.245
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    Magnetization (M), field induced magnetic anisotropy (Ku), rotational hysteresis loss (Erot) and melting point (Tm)f water- and paraffin-base ferrofluids were investigated in a temperature range from 77 K to 300 K as a function of the density of colloidal particles. Both paraffin and paraffin-base fluids were melted down at the temperature range from 180 to 210 K. In this range, the values of M and Erot, for paraffin-base fluids increased and Ku decreased with increasing temperature. These properties are interpreted by assuming that liquid-state and solid-state parts in paraffin exist in this tempetarure range and that the volume of solid-state part decreases with increasing temperature. The freezing point depression was observed in water-base fluids.
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  • Magnetic Properties of Amorphous Dy0.21Fe0.79 Thin Film with Random Anisotropy: Observation of Anomalous Hall Effect and Magnetic Kerr Effect
    T. Saito, J. Maedomari, N. Ohmura, K. Shinagawa, T. Tsushima
    1989 Volume 13 Issue 2 Pages 249-252
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.249
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    By complementary measurements of magnetization. Hall resistivity ρH, and magnetic Kerr rotation θK, magnetic properties of amorphous Dy0.21Fe0.79 thin film with random (and coherent) anisotropy were investigated in several magnetic fields as a function of temperature. An irreversibility is observed below a certain temperature for ρH and θK as well as magnetization, and an anomalous negative magnetization and no changes of sign in ρH and θK are found near the compensation temperature. This latter seems to be a non-equilibrium phenomenon characteristic of ferrimagnet with both random anisotropy and compensation temperature.
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  • Magnetoelastic Effects of Fe-Pd Base Alloys
    M. Kikuchi, T. Nakayama, S. Kadowaki
    1989 Volume 13 Issue 2 Pages 253-256
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.253
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    The magnetoelastic properties of Fe-Pd+Mo, Ni, C and Si ternary alloys have been studied. The γ phase was stabilized at room temperature by their addition. The linear magnetostriction λ//, ΔE effect and dλ///dH increase in the ternary alloys. Magnetomechanical coupling constant κ obtained from ΔE effect agrees with that calculated from dynamic magnetostriction. The maximum value of κ is 0.26 at a bias field of 8 Oe.
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  • Magnetic Moment and Curie Temperature in Amorphous Co-R Alloys
    Yang Xing-Bo, S. Ishio, T. Miyazaki
    1989 Volume 13 Issue 2 Pages 257-260
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.257
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    The magnetic properties of amorphous Co100-xYx (50 ≤ x ≤ 70) alloys prepared by melt-quenching method were studied. Based on the results derived from the Co-Y alloys, the magnetic moment of Co and the Curie temperature in amorphous Co100-xRx (R=Pr, Nd, Sm, Gd, Dy, Er) alloys were discussed. The Co atoms no longer sustain a moment when x ≥ 60. The exchange integral between R and R or R and Co atoms rapidly decreases as the atomic number of lanthanides increases.
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  • Magnetostriction of Amorphous Pr0.2(Fe1-xCox)0.8 Alloys
    S. Ishio, S. Takahashi, T. Miyazaki, S. Kadowaki
    1989 Volume 13 Issue 2 Pages 261-264
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.261
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    Magnetostriction of amorphous Pr0.2(Fe1-xCox)0.8 alloys (0 ≤ x ≤ 0.6) and Pry(Fe0.8Co0.2)x(Si0.43B0.57)z (0.7 ≤ x ≤ 0.85, 0.15 ≤ y ≤ 0.3, 0 ≤ z ≤ 0.3) alloys has been measured in the temperature range from 77 to 400 K. The value of magnetostriction λ (λ=(2/3)[(Δl/l)// - (Δl/l)⊥]) for Pr0.2(Fe1-xCox)0.8 exhibits a maximum at x =0.2; it is about 760×10-6 at 77 K and 260×10-6 at room temperature. Temperature dependence of the magnetostriction is descussed in terms of the singleion model.
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  • Matteucci Effect in Amorphous Wires with Negative Magnetostriction
    H. Takamure, J. Yamasaki, K. Mohri, I. Ogasawara
    1989 Volume 13 Issue 2 Pages 265-268
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.265
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    Matteucci effect was studied on Co-Si-B amorphous wires with negative magnetostriction. It has been shown and confirmed exprimentally that the Matteucci pulse voltage appearing between wire ends is proportional to the length of propagating domain boundary in a reverse way to pulse voltage associated with Barkhausen discontinuities. An attempt was made to increase Matteucci voltage with thermal treatment. Simultaneous application of torsion and tension during annealing was found to increase Matteucci voltage by one order of magnitude over that of as-quenched wires.
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Magnetic Thin Films
  • Xe Ion-Implanted NiFe Thin Films−Behaviors of Xenon and Magnetic Properties
    K. Uematsu, S. Tsukahara S. Tsukahara, T. Iwashima, H. Tanoue
    1989 Volume 13 Issue 2 Pages 269-272
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.269
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    A systematic experiment on xenon ion implantation into permalloy films was made in order to understand the effects of implantation of heavy inert ions on microstructures and magnetic properties. Xenon ion implantation always caused crystallization of the partially epitaxially grown permalloy film, so that the grain size increased. In addition, spherical bubbles were clearly observed even at low fluence in slightly defocussed TEM image. The bubble size varied to several 10 A with the fluence. In an electron diffraction pattern a weak extra halo ring became visible when the fluence exceeded about 6×1016/cm2. Magnetization measurement showed a large decrease in Ms and Meff when the fluence increased. Origin of the decrease of magnetization was discussed in relation to xenon bubble formation, and is probably attributable to a decrease of magnetization of permalloy atoms on the bubble surface.
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  • Magnetic Anisotropy of Ni Films Prepared by Ion Beam Sputtering
    K. Sato, T. Imai, H. Kondo, T. Mizoguchi
    1989 Volume 13 Issue 2 Pages 273-276
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.273
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    The magnetic anisotropy in Ni films deposited by ion beam sputtering (IBS), triode rf sputtering and diode rf sputtering, was studied in relation to the internal stress in the films. Strong in-plane easy magnetic anisotropy (Ku∼-5 ×105 erg/cm3) was observed in IBS Ni films deposited at an acceleration voltage above 1 kV at room temperature. The internal compressive stress was found to be as large as -1.2×1010 dyn/cm2, which causes a stress-induced magnetic anisotropy of about -1.2×106 erg/cm3 in the IBS Ni films. There is some positive contribution to the magnetic anisotropy, possibly due to anisotropic internal shape effect (Kint∼6 ×105 erg/cm3). Both this perpendicular magnetic anisotropy and the stress-induced in-plane anisotropy are reduced with increasing substrate temperature during deposition. It is possible to obtain a stress-free isotropic IBS Ni film at an appropriate substrate temperature (250∼300°C) and an acceleration voltage (1.1 kV) of the ion beam
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  • Structure and Magnetic Properties of Sendust/Under-Layer Films
    A. Ashida, M. Hattori
    1989 Volume 13 Issue 2 Pages 277-280
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.277
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    The Sendust MIG (metal-in-gap) head has been developed for high density recording systems. Aloxidization at the boundary between the Sendust film and MnZn-ferrite, however, degrades the soft magnetic properties and insertion of Ni-Fe film between them is effective to rectify this problem. In the present paper, the effects of Ni-Fe film insertion are investigated in detail and the following results obtained: 1) X-ray diffraction intensity of (110) plane for the Sendust film on Ni-Fe/MnZn-ferrite is stronger than that on MnZn-ferrite. 2) Ni atoms in Ni-Fe film diffuse into the Sendust film with annealing at over 550°C. 3) Little degradation of permeability and coercivity is observed for the Sendust film containing Ni less than 1.4 wt.%
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  • Soft Magnetic Properties of Fe-Ni-Nb Alloy Films
    T. Shimatsu, M. Takahashi, H. Uwazumi, T. Sato, M. Takahashi, T. Wakiy ...
    1989 Volume 13 Issue 2 Pages 281-284
    Published: April 30, 1989
    Released on J-STAGE: December 07, 2007
    DOIhttps://doi.org/10.3379/jmsjmag.13.281
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    Relation between soft magnetic properties and local anisotropy fluctuation in Fe-Ni-Nb alloy films measured by the dynamic differential susceptibility method was clarified and discussed in comparison with Fe-Si-Al alloy films. In Fe-Ni-Nb alloy films, excellent soft magnetic properties, μeff=6500 at 5 MHz of 1000Å film thickness, were realized. In Fe-Si-Al alloy films, the magnitude of μeff is proportional to 1/√S (S: structure constant) and independent of the value of HK, while in Fe-Ni-Nb alloy films, the value of S is about one tenth of that in Fe-Si-Al alloy films, and the magnitude of μeff is not dependent on the value of S. Rather, this magnitude is dependent on the value of Hk, and is almost equal to 4πMs/Hk (obtained from a rotational magnetization model in a uniaxal single domain particle).
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