In-plane crystalline orientation of a longitudinal thin film medium was investigated to clarify therelation between the crystalline orientation and the magnetic anisotropy. The anisotropy is induced by deposition with moving disk substrate (transport deposition) and changed by texturing on the substrate, as is well-known. It has heretofore been difficult to measure the crystalline orientation by X-ray diffraction because of the giant background reflection. We have developed a precise background correction method in order to measure the pole figure of the longitudinal medium. In conclusion, it is clear that the c-axis of the medium on a plane substrate is almost oriented to the moving direction of the substrate and the axis of the medium on a textured substrate has a tendency to orient to the texturing direction.

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Magnetic properties were investigated for CoNiCr/Cr films sputtered on polished glass at T_s ranged from 25 to 400°C in connection with microstructure. H_c was found to increase when increasing T_s for CoNiCr/Cr films, which consisted mainly of h. c. p. phase. Microscopical elemental analysis by electron beam revealed that Cr as underlayer diffused gradually into grain boundary of CoNiCr films and into each grain of CoNiCr with higher T_s. Torque loss analysis was made to determine the magnetic isolation among CoNiCr grains. Uniaxial magnetic anisotropy field of each grain determined experimentally H_k^grain (exp.) was found to increase when increasing T_s. Metalgraphical change promoted magnetic isolation among h. c. p. CoNiCr grains and as a result, microscopical demagnetizing field in each CoNiCr grain increases. This conclusion is well supported by the present experimental results of the torque loss analysis.

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Magnetization reversal in Co-Ti-Cu-added γ-Fe₂O₃ thin films, formed by sputtering and heat treatments, was studied. The crystal grain size dependences of coercivity show that the most possible reversal mechanism is fanning mode. The coercivity decreases with decreasing grain size because thermally activated magnetization reversal takes place. Rotational hysteresis integrals for the films ranged from 1.47 to 1.58 which are equal to those of fanning mode.

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Crystallographic and magnetic properties of Baferrite films prepared by the sol-gel-pyrolysis method were investigated. A solution of Ba- and Fe-nitride dissolved in ethylene glycol becomes a gel with an appropriate viscosity by supersonic stirring at 80°C The films are spin-coated onto SiO₂/Si substrates, dried and then heated in air at various temperatures.In the films prepared in the conditions of composition ratio of Fe₂/Ba=5, drying temperature T_d=250°C and crystallizing temperature T_c=800°C, single-phase Ba-ferrite was obtained, and their σ_10K and H_c were 47.0 emu/g and 3∼4 kOe, respectively. The films prepared at T_d=250°C have flat surfaces without any cracks. In the thin films whose thickness is 900Å, preferred orientation of c-axis was observed.

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In this paper we introduce barium-ferrite tape samples with a high recording characteristic in the conventional longitudinal magnetization mode, and explain the origin of their high output voltage at high recording densities, referring to the effect of magnetic characteristic and the behavior of remanent magnetization. Longitudinally and non oriented barium-ferrite recording media are prepared with the same magnetic paint from one barium-ferrite magnetic powder. The prepared barium-ferrite tapes are inferior to ultra high density metal tapes in regard to surface roughness and magnetic energy, but exhibit better recording characteristics at high recording densities more than about 80 kFRPI.
In particular the origin of high recording characteristic for the longitudinally oriented barium-ferrite tape samples may be explained rather by the effect of remanence curves on this sample than by perpendicular magnetization.

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A rapid, non-destructive optical method of detecting the perpendicular orientation at surface in metal LIPS tape is described. This technique uses reflection anisotropy due to depolarization coefficient anisotropy of the metal needle particles. A tape sample with less anisotropy by this evaluation showed higher density characteristics in wavelength response.

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Double layered magnetic coating media were made in order to obtain excellent electromagnetic conversion characteristics in wide frequency range. Video luminance signal is recorded only from a tape surface to 0.3μm in depth. However, video chrominance signal is reorded ranging from a tape surface to 0.6 μm in depth. By utilizing these characteristics, high coercivity magnetic particles which are suitable for recording high frequency signals, are able to be used for the upper layer. However, these characteristics are affected by the thickness of the upper layer and the coercive force of each layer. Therefore these values should be decided carefully considering recording depth of each of each signal.

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Correlation between magnetic properties and microstructure of the electroless-plated CoNiP perpendicular magnetic recording media was investigated. By adjusting the plating bath factors, the perpendicular coercivity, H_c(⊥), of the film can be controlled up to 1500 Oe without changing saturation magnetization, M_s, and the feature of the M-H loops. The reflection high energy electron diffraction analysis clarified that these films consist of the mixture of the <002> perpendicularly oriented hcp crystal region and the fcc crystal region without obvious crystal orientation. The increase in ratio of the <002> oriented hcp crystal region in such a mixing condition makes the H_c values higher, and finally the 1500 Oe film consists of almost of the <002> oriented hcp crystal region. The transmission electron microscopy observation revealed that the grain size increased up to about 0.03μm with an increase in the H_c(⊥), up to 1500 Oe. It was also clarified that these films have the initial regions with low H_c, consisting of fine crytallites with low crystal orientation.

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Spinel ferrite Co_0.10Fe_2.90O₄ film of 0.21 μm thickness was formed by plasma assisted MO-CVD using mixed vapor containing Fe(C₅H₇O₂)₃, Co(C₅H₇O₂)₃, and O₂ on a glass disk substrate, whose saturation magnetization and coecivity in the direction normal to the film plane at 8 kOe were 210 emu/cc and 1250 Oe, respectively. X-ray diffraction patterns and SEM image of the film showed that the film had columnar structure with <100> preferred orientation. Magnetic recording tests were performed for the disk using a MIG type ring head of 0.25-μm gap length at relation speed of 9.4 m · s^-1 and flying height of 0.1 μm. The recording density D₅₀ was 75 kFRPI and the reproduced waveform at 2.7 kFRPI showed dipulse containing longitudinal component.

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Incident angle dependence of magnetic properties of vacuum deposited Co-Cr films was investigated. With a continuous vacuum deposition system, “continuous films” and “fixed films” are deposited on polymer-substrates moving and stopping, respectively, with incident angle of evaporated atoms from 70°(initial) to 40° (final). In fixed films, which are cut into small pieces for measurements at every incident angle region of 2.5°, hcp c-axis dispersion increases and shape magnetic anisotropy becomes large with increases in the incident angle. In continuous films, both magnetocrystalline anisotropy and shape magnetic anisotropy contribute to the magnetic anisotropy. Compared with fixed films, magnetic properties of continuous films are influenced by initial film growth region with incident angle above 60°.

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A new sputtering source (named SPT target) has been proposed, aiming at improvement in a continuous sputtering system for a Co-Cr double layer perpendicular recording medium. Very low discharge voltage was realized compared with sputtering source targets for magnetic medium so far proposed. Both Permalloy and Co-Cr films deposited by the source showed high crystal orientation even at a high-rate deposition. High through-input of Permalloy and Co-Cr layers deposition corresponded to higher 2nd peak ratio and D₅₀* on recording density response for the resulting media. It was shown that the new SPT target is preferable for getting a high through-put in a magnetic recording medium production.

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Reproduced envelope of VCR head output will vary depending on the combination of magnetic head contour shape and tape stiffness, with low stiffness tapes in particular having damped envelope. Head contour was measured by the interference ring method with spline interpolation. The change of the head contour through wear has various patterns according to the head construction. Head shape dependence and tape tension dependence of reproduced envelopes were studied in connection with the tape stiffness. Reproduced envelope decreases with the increase of the radius of curvature for transverse direction of the head surface. Envelope improvement will be obtained by choosing the best position of gap on the head contour for each head construction, and by decrease of tape tension and head protrusion.

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Head-disk-interface of negative pressure slider is evaluated. The damage at seeking and tracking is from the dust invading the spacing between the slider and the disk, wearing down the disk surface. Occurrence is suppressed by controlling of cleanliness and wear rate of disk surface. The slider does not contact the disk even at 0.1μm flying height, because damage does not occur at high cleanliness. Cleanliness and wear rate of disk surface are selected as stress for acceleration life test. The results indicate that the interface has a high life span of over 300,000 hours. In start-stop method using loading/unloading, the slider has no damage for over 30,000 cycles.

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The durability of carbon protective layers of thin film magnetic disks was examined with pin-on-disk test, and the wear cross section was estimated as worn quantity. However, measuring the precise wear cross section is difficult because the worn quantity formed with this test is very small. Therefore, the Electron Probe Micro Analysis (EPMA) with Energy Dispersive X-ray Spectrometer (EDS) was tried to measure the worn quantity. If the thickness is thin, the characteristic X-ray intensity is proportional to the film thickness of the irradiated region However, it is well-known that hydrocarbon contamination induced by electron beam irradiation occurs. The influence of the contamination was suppressed by wide electron beam scanning. Furthermore, the acceleration voltage was optimized to maximize the peak-to-background ratio and sensitivity. High accuracy of this method is clarified in this paper.

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Recently, the demand for making hard disk drive to high capacity and small strengthens by joining to the market of portable computer. Reproduced output depend on medium velocity on inductive head. It is an obstruction to get a large capacity in the small diameter hard disk drive. However, the MR element has domination that large output is obtained in the drive on small diameter hard disk drive which slows of the medium velocity because the reproduced output doesn't depend on the medium velocity. So MR head is paid attention as a magnetic head which achieves making the small diameter hard disk drive to a large capacity. Then, shunt bias In-Gap type with the MR element in the gap and SAL (soft adjacent layer) bias piggyback type with MR element out of gap were made for trial purposes and these two kinds of recording. characteristics were examined in this research. In SAL bias piggyback type of width 4.0μm of the read track, the error rate of 10^-12 and 300 μ V_p-p were obtained at 28.6 kFCI.

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A new fast algorithm for reconstructing stray magnetic fields of a magnetic head by electron beam tomography and its application are presented. We have already proposed the 3-D reconstruction method of stray magnetic fields using ART method for electron beam tomography. In this new algorithm, magnetic field distribution on a measurement plane just beyond the gap is first reconstructed using ART method. Then the entire magnetic field distribution is calculated numerically by boundary element method using the reconstructed magnetic field on the measurement plane as a boundary condition. Using this method, total reconstruction time is shortened and reconstruction accuracy is quite improved. An example of reconstruction of magnetic field of an MIG head is described. From these results and also analytical results by 2-D finite element method, it is shown that the new algorithm is useful in reconstructing the entire magnetic field distribution rather accurately.

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This paper describes a relationship between transition lengths and head fields with media of various coercivities. The transition lengths were written by a single sided and a double sided MIG head on three thin film media which have the coercivity of 874, 1121 and 1270 Oe. The transition lengths were surveyed through the colloid SEM observation. The head fields of the MIG heads were analyzed by the finite-element method (FEM) with magnetic saturation taken into account. The following phenomena were found. First, the 2nd fields stray from saturated ferrite region near the interface between a metal film and ferrite core of the MIG head. Second, the transition lengths are spread by the influence of the 2nd field when the strength of the 2nd fild is higher than a half of the media coercivity. On the other hand, if the media coercivity is two-times higher than the 2nd field strength, the transition length is strongly related to the field gradient of the primary field at the recording zones.

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A new parameter ΔH_c on M-H minor curves is introduced to estimate the standard deviation of the H_k distribution. The ΔH_c correlates strongly to coercivity squareness s* and half-width of switching field distribution SFD. and needs no compensating for the demagnetizing field in perpendicular recording media. It was shown by computer simulation analysis that the magnetic recording performance depends greatly upon the particle's anisotropy field H_k distribution in recording media as well as coercivity and saturation magnetization. The narrow H_k distribution of Co-Cr sputtered media is derived from the high crystallinity, and leads to superior performance in high density recording.

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Investigated is recording chracteristics of Co-Cr films with regard to incident angle of evaporated atoms onto a substrate. Recording characteristics of the Co-Cr films deposited with incident angle from 55° to 20° depend on head scan direction. In normal direction, recorded magnetization of the film is mainly dominated by magnetic field near the leading edge of a head, while in reverse direction, it is mainly dominated by the field near the trailing edge. Singlepeak-like isolated waveform in normal direction of head scan is explained by superposition of waveform reproduced from magnetization recorded by the magnetic field near the leading edge and waveform from magnetization reversed only in the film surface by magnetic field near the trailing edge. Reproduced voltage of the film decreases with increasing the azimuth angle owing to the magnetic anisotropy existing in the film plane,, while Co-Cr films deposited with incident angle from 20° to −20° have almost the same density responses at different azimuth angles.

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Recording and reproducing characteristics of a Co-Cr perpendicular magnetic hard disk with a thin Fe-Co back layer were investigated by non-flying type MIG head. The Co-Cr/Fe-Co composite media were made by R.F. sputtering on glass substrate with Cr underlayer. Results show that a reproduced isolated pulse of the medium has a single peak with a large amplitude. The head gap length was a dominant factor to the upper limit of the recording density. Using a MIG head whose gap length is 0.15 μm, D₅₀ of 120 kFRPI and normalized output of 95 nV_0-p/μm · turn · m/s can be achieved. Furthermore, when the thickness of Co-Cr layers was increased, the output voltage became larger, but Over-Write characteristics

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The effect of domain structures of main-pole films on reproducing sensitivities were investigated for various single pole type perpendicular magnetic heads. The reproducing sensitivity of the heads made of a Co-Zr-Nb single layer becomes unstable and decreases with the increase of closure domain size when the track width narrows and the anisotropy field H_k decreases. On the other hand, when the wall of closure domains can be pinned by grooving at the only edge of a main-pole film, the magnetization rotates without any disturbance in main domains. Using this novel domain control method, closure domains become smaller even for smaller H_k, an d a stable and highly sensitive single-pole head can be obtained.

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Up to now, the return-path core of a single-pole thin film head for perpendicular magnetic recording was at a definite distance in the head scanning direction. In this type of head, distortion of the reproduced waveform due to an extra pulse arising when the return path core comes into direct contact with the medium increases. In order to eliminate this distortion, we developed a new shaped single-pole thin film head with the return-path core at a definite distance to one side in the track width direction. This head is called the FiTR head (single-pole thin Film head with Transverse Return path core of flux flow). The recording field distribution and reproducing characteristics of the head were investigated by simulation and experiment. The new shaped thin film head has high sensitivity, an excellent recording field distribution and there is no distortion of the reproduced waveform.

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The recording charateristics of single pole thin film head was investigated. Both narrow track and high linear recording density are necessary in order to make high area recording density possible. Single pole thin film head in which main pole thickness is changed from 0.15 μm to 1.1 μm were manufacture for trial. By using Co-Cr-Pt/Ni-Fe perpendicular magnetic recording medium, recording characteristics were examined. As a result, at 0.2μm of main pole thickness, characteristics of CN ratio: 41 dB, media noise: 2.4μVrms overwrite −30 dB were confirmed.

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Contact perpendicular magnetic recording on both sides of a hard disk was tried introducing a head suspension with a spring movable in up and down directions. Head-to-medium spacing of about 300A is maintained up to 11 m/s at all tracks on the disk. Results show that the distribution of magnetic properties of the recording layers on the hard disk directly reflects on the envelope and the recording and reproducing characteristics. Data recording was successfully performed at 100 kFRPI and track width of 60μm.

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The effects of oxygen in Ar/O₂ mixed sputtering gas on the magnetic and magnetooptical properties of PtMnSb films, prepared by rf sputtering, were investigated. In addition to PtMnSb phase, growth of Mn₂Sb, PtSb₂, oxides of Mn and Sb were observed for PtMnSb films at low total gas pressures of the sputtering gas. The saturation magnetization M_s decreases with a decrease in the total gas pressure, leading to improvement of the magnetic perpendicular anisotropy of the films. The change in the Kerr rotation angle θ_Kp with a decrease in the total gas pressure is small as compared with the change in M_s, and θ_Kp/M_s increases at low total gas pressures.

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Followed by our previous study on bismuth and chrome added Mn₂Sb films formed by vacuum evaporation, we have investigated magnetic and magneto-optical properties of tin substituted Mn₂Sb (Mn₂Sb_1-xSn_x) films, where x was changed from 0 to about 0.40 (Sn 13.2 at%). The reason why tin was chosen as the third element is that there are two magnetic intermetallic compounds having different types of crystallographic structure in this system, namely Mn₂Sb has tetragonal structure, while Mn₂Sn has hexagonal structure. As the amount of tin substitution increases, the diffraction lines from Mn₂Sb become weak and the saturation magnetization decreases but perpendicular magnetization films can be obtatined up to x=0.40 (Sn 13.2 at%). Results show that the shrink of the c-axis of Mn₂Sb crystal occurs in the vicinity of x=0.15 (Sn 5 at%), where the decrease in coercivity and the increase in polar Kerr rotation are observed. These are considered to be closely correlated phenomena, reflecting presumably, the change in electronic structure of Mn₂Sb.

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Films of MnBiAl composition, prepared by interleaving Mn and Bi layers by vacuum evaporation into a multilayer with an AI-layer at half-thickness, were studied. For Mn contents of 40 to 70 at% and AI dopings below 15 at%, the films, when annealed at temperatures between 230 and 420°C, became ferromagnetic with magnetization perpendicular to the film plane. Adding AI caused the film crystallite size to decrease to about 50 nm, and to depress the phase transitions between the low (lhp)- and high (htp)- temperature phases. Compared with MnBi films, no significant changes in crystal structure, lattice constants and Curie temperature were observed. The Kerr rotation spectrum shows a maximum value of 1.78° at about 700 nm and a peak of 1.5° at 370 nm. The reflectivities vary from 40 to 60% with wavelength change from 330 to 800 nm.

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The longitudinal Kerr magneto-optic effect of evaporated Fe-Ni, Ni-Co and Fe-Co binary alloy films was measured in order to make clear the relationship between the Kerr magneto-optic effect and the saturation magnetization M_s. Results show that the relationship between the Kerr rotation θ_k and the M_s can be expressed by θ_k∝ M_s^1.7∼2.1 at λ=400∼1000 nm. The magneto-optic parameter amplitude, Q₀, which is a measure of magneto-optic effect, is not only dependent on the M_s, but also on the crystal structure.

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Photoinduced decrease in magnetic initial permeability below 20 kHz is observed at 77 K in yttrium iron garnet (YIG) single crystal with a small amount of Ga (0.0625) and some oxygen deficiency. On warming the previously illuminated sample with a white light, the complex permeability was found to show the photoinduced disaccommodation and triple peaks of the imaginary part of permeability, μ" as a function of temperature. Furthermore, it is observed that each peak of μ" depends on the illuminating time. These features are discussed and interpreted, based on a modified “two center” model.

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Fe, Ni, Cu and MnSb fine particles were prepared in various Ar pressure (10^-4∼5.0 Torr) and were dispersed in a liquid (arkylnaphthalene with 10 vol% surfactant). The mean diameter of Fe particles increases from 20Å to 180Å and that of MnSb particles from 160Å to 280Å with increasing the Ar pressure at which the particles are prepared. Fe and Cu particles were oxidized and MnSb decomposed to Mn and Sb when the pressure was low. Faraday rotation, θ_F, of these liquids was measured for various concentrations of particles. The θ_F decreased with decreasing the concentration of particles. These results agree well with the calculated values by assuming that particles are dispersed homogeneously and make no interactions with one other.

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Cu-added polycrystalline Bi-substituted iron garnet films were prepared on glass substrate by RF diode sputtering and post annealing method. The addition of 3.4 at%Cu was effective both on decreasing the size of crystals to about 1 μm and on increasing the coercivity to 5.4 kOe. The shape of the statically recorded bits was also improved.

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The structure and the magnetic properties of Co- Pt alloy thin films were investigated under various sputtering conditions. Co-Pt films below 15 at%Pt had hcp structure and above 30 at%Pt fcc structure. The films of 15∼30 at%Pt indicated both of the hcp and fcc phases. Perpendicular magnetization was realized in the range of 20∼40 at%Pt. Substrate bias of −50 V improved the orientation of fcc [111] axis normal to the film plane and increased perpendicular anisotropy energy K_u. There was also a correlation between the orientation of the crystallites and K_u in the case of varying Ar gas pressure P_Ar. This suggested that perpendicular anisotropy of Co-Pt films arises from magnetocrystalline anisotropy. Although the perpendicular coercivity was small in these films, it increased by a factor of 2 with addition of 10 at%Cr.

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The purpose of this study is to investigate the leakage field from an auxiliary layer to a recording layer in an exchange-coupled multilayered magnetooptical medium. In order to estimate the leakage field, test media, in which an auxiliary layer was formed on a recording layer through a non-magnetic layer, were prepared. The leakage field was determined as the difference in the threshold external fields between two different initial magnetization directions in the recording test. The experimental result was in good agreement with the numerical calculation, in which a single domain nucleation was assumed. The leakage field was found to be proportional to the change in magnetization at the heated spot. It was also found that a leakage field of about 200 Oe was generated from the auxiliary layer with a magnetization change of 150 emu/cc.

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The spin-polarized electronic structure of an amorphous alloy was calculated in a Gd₃₃Fe₆₇ alloy for the first time, a result long awaited because it allows us to clarify the magnetic and magneto-optical properties. The calculated density of states of the Fe and Gd d-state show roughly a single peak structure. The resultant magnetic moment of Fe is 2.0μ_B, and shows good agreement with experimental value of 1.9μ_B. The contribution of each constituent atom to the Kerr effect is well manifested on the basis of the obtained electronic structure.

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The magneto-optical recording characteristics of three types of DyFeCo films with a quadri-layers structure were measured using three recording methods: the optical modulation method, magnetic field modulation method and the laser off method. In the laser off method, the laser power was lowered only while the magnetic field was changing.
As for carrier to noise ratio (C/N), the transitionmetal (TM) rich type medium was best with the optical modulation method. C/N with the magnetic field modulation was lower than that with optical modulation method. The three media were similar to the magnetic field modulation method.
The laser off method improved the C/N and the magnetic field dependence of the C/N. Especially TM rich type medium exhibited the same C/N value as in the optical modulation.

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The external magnetic field characteristics were investigated for the exchange-coupled quadrilayered magento-optical film that was applied to the direct overwriting by light intensity modulation. The external field dependence in recording characteristics was studied through the temperature dependence of the reversal field and mechanism of the direct overwriting. In the direct overwriting by light intensity modulation, the upper limit of the external field existed due to the low process. Here the initializing process of the writing layer that is unique to the quadri-layered film did not participate in the lower limit of the external field. Wide external field margin was obtained for a practical use. So the effective fluctuation of the external field did not affect the recording laser power margin.

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To investigate the magnetic contributions of each iron site in Nd₂Fe₁₄B, magnetic characteristics of Nd₂ (Fe_1-xM_x)₁₄B (M=Al, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Pt) have been measured and preferential occupation of M atoms in Fe sites have been determined by Mossbauer spectroscopy. Mössbauer spectra are analyzed by our original method of analysis which take into account the effect of environments and the degree of preference in each Fe site. These analyses have revealed that T_c increases with the expansion of the lattice parameter c when the k₁ and j₁ sites are preferentially substituted by M atoms while it decreases when the j₂ site is preferentially occupied by M. It seems that ferromagnetic interaction between Fe layers increases by the expansion and decreases with the occupation of M atoms in the j₂ site. On the other hand, T_s decreases when the c site is preferentially substituted. This fact suggests that T_s relates to interaction between Fe and Nd atoms.

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Magnetizing field dependence of the magnetic viscosity parameter S_v was measured for aligned and non-aligned Nd-Fe-B sintered magnets on demagnetizing curves at room temperature. Remarkable change of magnetic aftereffect was observed in the range of lower magnetizing field. Relation between S_v and coercivity depending on magnetizing field was studied.

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Sputtering conditions for synthesis of anisotropic Nd-Fe-B thin film magnets were studied. Results show that the film composition as well as substrate temperature are important parameters in affecting the c-axis orientation of the Nd-Fe-B tetragonal compounds. It was shown that the anisotropic thin film magnet with the easy axis of magnetization normal to the film plane could be deposited by choosing the composition near Nd₁₃Fe₇₀B₁₇ at substrate temperatures as low as 460°C which is fairly below the previously reported value. The anisotropic thin film magnet exhibited the intrinsic coercivity of 7 kOe and the maximum energy products of 20 MGOe. The potential application of thin film magnets to microactuators and motors was demonstrated by fabrication and operation of 5mm diameter pulse motor using the obtained anisotropic thin film magnet.

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Structure, magnetic properties and corrosion resistance of sintered, anisotropic Nd-Dy-Fe-Co-B-(V or Mo) permanent magnets are reported. Addition of a few atomic percent of V or Mo is found to be beneficial in that it enhances the intrinsic coercivity (H_cJ) without sacrificing much of remanence or the maximum energy product especially when a substantial amount (ca., 5 at%) of Co is present. Thus, Co-addition of V or Mo and Co serves to improve both corrosion resistance and temperature stability of the magnetic properties. Possible reasons for the enhancement of H_cJ due to V and MO are also discussed.

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The formation and magnetic properties of CaCu₅, Th₂Zn₁₇ and PuNi₃ type compounds were investigated for (Fe_1-xCo_x)_4.5Al_0.5Sm and (Fe_1-xCo_x)_4.5Ni_0.5Sm alloys rapidly-quenched at various disk velocities ranging from 8.4 to 41.9 m/s. The CaCu₅ type (Fe_1-xCo_x)_4.5(Al, Ni)_0.5Sm compounds were formed in the composition range 0.6≤x≤1.0. The formation range is the same as that without addition of Al and Ni. The different point due to the addition of Al and Ni is that the CaCu₅ type compound can be formed at lower disk velocities, indicating the increased stability of the compound. Its unit cell volume does not change with the addition of Al and Ni. On the other hand, the unit cell volume of (Fe_1-xCo_x)₁₇Sm₂Al_δand (Fe_1-xCo_x)₁₇Sm₂Ni_δ(x≤0.6) compounds increases 2∼4% and 1∼2%, respectively. The particular large increase of the unit cell volume of (Fe_1-xCo_x)₁₇Sm₂Al_δ is considered to enhance the Curie temperature and the coercivity.

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We investigated the magnetic properties of melt spun Pr₂Fe₁₄C and several pseudoternary compounds of the type Pr₂(Fe, M)₁₄C and (Pr, R)₂Fe₁₄C. A value of iH_c∼1.3 kOe was obtained in Pr₂Fe₁₃MnC alloy ribbons. Heavy rare earth substitution leads to an increase in room temperature intrinsic coercivity. A value of iH_c=3 kOe, 6 kOe was achieved for (Pr_0.6Gd_0.4)₂Fe₁₄C, (Pr_0.6Dy_0.4)Fe₁₄C alloy ribbons, respectively, and large intrinsic coercivity of 18 kOe was found in Pr_7.9Dy_5.2Fe_79.7C_7.2 composition.

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Magnetic properties and microstructures of Pr- Fe-B (Ga) melt-spurn ribbons prepared by single or twin-roller were studied. The texture with the c-axis normal to the surface was observed in slowly quenched ribbons, and shows a strong dependence on composition. Ga addition is effective in increasing the coercivity and the c-axis alignment of the ribbons. Magnetic measurement of the ground powders of the ribbons quenched by twin-roller shows that the powders solidified in a paraffin bath with applying a magnetic field of 12 kOe show high coercivity of iH_c= 13.8 k0e and higher remanence than those withowt applying a magnetic field. Microstructural observations of cast alloys suggest that the strong c-axis alignment arose from the rapid-quenching.

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Rotational dynamic magnetostriction (RDM) was measured as a function of rotating magnetic flux density on nonoriented and grain-oriented silicon steel sheets under various magnetization conditions. Rotational dynamic magnetostriction was measured by using the two-dimensional strain gauge,which provides x- and y-direction output. The rotational dynamic magnetostriction in silicon steel sheet is larger than the alternating magnetostriction along the rolling direction.

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The magnetic properties of silicon steel sheet under the condition of two-dimensional excitation (circular, elliptic and alternating with rotation of the direction) are investigated. Two-dimensional magnetic measurement is a generic term introduced recently to comprise the measurement of magnetic properties of a specimen under the condition of rotating magnetic induction. Two-magnetic properties in silicon steel sheet are very sensitive to the axis ratio and the inclination angle of the magnetic flux density of longitudinal axis,because that is very effective to the anisotropy of the sheet.

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Contribution of superimposed higher harmonics to magnetic losses in electrical iron sheets was examined at power frequencies. Results show that magnetizing processes by the PWM voltage excitation are similar to those by the ac magnetization superimposed with a carrier frequency magnetization and are different from those by the rectangular voltage excitation having the same voltage height and the same exciting duration having a large amount of lower order higher harmonics. As a result we have proposed a practical measuring method for the magnetic loss equivalent to that under the PWM voltage excitation.

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The frequency dependence of permeability μ_i in amorphous Co-Fe-Si-B wires was investigated as a function of wire diameter, annealing temperature, tensile stress and drawing parameters. Results show that the level of μ_i and the critical frequency to maintain μ_i constant were mainly dependent on wire diameter, suggesting the eddy current effect on μ_i at high frequencies. Furthermore, the two stage annealing in which drawing and annealing were alternatively repeated twice was found to result in improving the frequency characteristics of μ_i.

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Damping constants of domain propagation, due to eddy current and spin-relaxation, in Fe-Si-B amorphous magneto-strictive wires were estimated. The damping constant in the outer shell of wire was about 57% of the total damping constant. Domain observations of the wire surface before and after the Large Barkhausen discontinuities were experienced. It was considered that this remarkable large damping in the outer shell was caused by a magnetic interaction between the core and shell of wire, which was taken place during propagation of domain wall in the core.

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The effects of Cr addition into nanocrystalline Fe- Cu-Nb-Si-B alloys on the soft magnetic properties and chemical characteristics were studied. Corrosion resistance of the nanocrystalline alloys annealed in non-oxidizable atmosphere is better than that of the pre-annealed amorphous alloys. A small addition of Cr and the use of non-oxidizable annealing atmosphere are very effective in improving the chemical properties of the nanocrystalline alloys. Fe_72.5Cr₁Cu₁Nb₃Si_13.5B₉ alloy exhibits both high permeability of about 75000 and exellent corrosion resistance.

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Magnetostriction of (Fe_1-xCo_x)₃Tb (0≤x≤1.0) compounds and amorphous Fe₃Tb alloy were measured at room temperature and 77K. The value of λ_//λ_⊥ at 20 kOe of (Fe_1-xCo_x)₃Tb compounds increases drastically from 1500×10^-6 to 3000×10^-6 with increases in x from 0 to 1.0 at 77K. The value of λ_//λ_⊥ for amorphous Fe₃Tb is about 30-40% smaller than that for the crystalline one. The effect of Co substitution on magnetostriction of (Fe_1-xCo_x)₃Tb compound is discussed based on the single ion model. The magnetic field dependence of magnetostriction in Fe₃Tb amorphous alloy is also discussed in connection with magnetization process.

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