The effects of strain in a magnetic film on the coercive force of CoCrTa longitudinal thin-film media were studied. A wide range of in-plane coercive forces (1900-2600 Oe) was obtained by depositing a CoCrTa film on Cr and CrTi alloy underlayers of various thicknesses. The residual in-plane Strain was meaSured by X-ray diffraction. Compressive strain of up to 3 × 10^-3 existed in the magnetic films. The magnitude of the in-plane strain was affected by the thickness and material of the underlayer and the substrate bias. The coercive force was enhanced by the inplane compressive strain, that is consistent with a negative magnetostriction constant. The relative change in the coerciVe force was estimated atabout 220 Oe per 1×10^-3 strain.

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The effect of heat treatment conditions on the magnetic properties of Zr/CoNiCr alloy/Cr heat-treated media was investigated. When the heating rate, holding time, and cooling rate were 220°C/min, 1 s, and 1000°C/min, respectively, the same magnetic properties were obtained as in the standard conditions, that is, a heating rate of 90°C/min, a holding time of 60 s, and a cooling rate of 13°C/min. From the results of XPS analysis, it was found that Cr diffused from the Cr underlayer into the CoNiCr alloy layer with increasing heat treatment temperature, as in the standard conditions. Therefore, it is considered that an increase in H_c with increasing heat treatment temperature caused the Cr to be segregated from the Cr underlayer into the grain boundaries of the CoNiCr alloy, as in the standard conditions.

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The microstructural and magnetic properties of CoNiPt alloy films :with SiO₂ added were studied to determine the films' potential for use in high-density longitudinal recording media. The Si in the sputtered film is in the form of SiO₂ and is segregated at the grain-boundary. With the addition of the SiO₂, the grain size becomes smaller and grain separation becomes well developed. These changes in the grain structure are attributed to the presence of segregated SiO₂.The in-plane coercivity increases and media noise decreases significantly with an increase of SiO₂, while the crystal orientation dose not change. A magnetic ripple structure indicating the clustering of exchange-coupled grains fades out with the addition of the SiO₂. Thus, the well-developed grain separation due to the addition of SiO₂ is responsible for the excellent magnetic properties, which are suitable for high-density recording media.

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Ultra high-density-recording states were observed in magneto-optical (MO) and magnetic recording media, using particles prepared by sputtering. We clearly observed recording bits as small as 0.3μm in diameter for MO media,and also visualized the influence of the recording laser power on high-density recording states. The observation method also made it possible to observe ultra-high-density recording states (with a bit length of 0.08μm) in obliquely evaporated Co-CoO magnetic recording media. According to these experimental results, the resolution of the present method was estimated to be finer than 0.08μm.

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The effect of introducing oxygen into the deposition gas on Co-Cr film was investigated in a room temperature deposition method. When oxygen was added to Ar gas, the grain size of Co-Cr became small. As a result, the perpen- dicular coercivity of Co-Cr films was increased by the introduction of a small amount of oxygen into the Ar gas. Introduction of air into the gas was found to be even more effective than introduction of oxygen. However, too much oxygen or air degraded the perpendicular anisotropy and led to a decrease in coercivity.

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Interparticle interaction in magnetic recording media affects the recording characteristics, particularly the noise characteristics. We made a new simulator, based on the curling model and a direct method of calculating the interparticle interaction field, and examined how the interaction affects the magnetic characterisics of perpendicular thinfilm media. We also calculated and examined the magnetization patterns in perpendicular and londitudinal media.

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This article describes how the orientation of acicular particles in coatings decreases from the angle of the applied field as the coatings become dry. Understanding this phenomenon is very important for making obliquely oriented tapes with a definite orientation angle. Obliquely oriented coatings of CrO₂ particles were prepared in an electromagnet, and their structure was examined by X-ray diffraction, SEM observation, and magnetic measurement. It became clear that acicular particles in coatings show shrinkage disorientation depending on the coating depth.

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The track profile characteristics of MR heads with an NiO domain control layer were investigated. The track profile is affected by the sense current, the electrode distance, the MR height, and the distance of domain control layer. If the electrode distance is smaller than the MR height, the peak amplitude of the track profile becomes small.
We observed the track profiles on three types of head structure. In one, the domain control (DC) distance is wider than the electrode distance (type A). In another, the DC distance and the electrode distance are the same (type B). In the third, the DC distance is smaller than the electrode (type C).
The magnetic track width of type A is wider than that of type B, when their electrode distances are almost the same. The track profile of type B is strongly affected by NiO exchange coupling. The sensitivity of type B is smaller than that of type A.

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The thermal behavior of a shielded magnetoresistive (MR) head was studied by using the three-dimensional finite element method. The calculation results show that the joule heat generated in the track region of the MR element is mainly carried in the direction of the shield layers. The temperature rise in the shielded MR head is much lower than in an unshielded one. Increasing the thermal conductivity of the shield layers is effective for reducing the temperature rise, with increase in the sense current density. As the track region size decreases, the heat radiation efficiency decreases. Therefore,it is important to improve the thermal conduction to the shield layers in order to reduce the temperature rise fo rshielded MR heads.

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Our flux-guided magnetoresistive-read/inductive-write composite head, which we named the WING MR head after the shape of its wide flux-guides, is designed for very low flying height recording. The flux-guides are rectangular and wider than the read width to reduce Barkhausen noise from multi-domain activities of flux-guides. The WINGMR head also has very small coils so that it can be fabricated on a very small slider. Test results show good offtrack characteristics and high linear density resolution at a flying height of 0.03 μm. The wide flux-guides reduce Barkhausen noise without lowering offtrack performance.

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The characteristics of the output vs. applied field (ΔV-H) of spin valve (SV) sensors with longitudinal biasing magnets are studied by using a micromagnetic model. In the case of sensors without biasing magnets, a hysteresis arises in the ΔV-H curves owing to an irreversible motion of the domain wall. When the product of the saturation flux density B_s and the thickness t of the biasing magnets are equal to or larger than the B_s·t values of the free layer, the ΔV-H curves are reversible. When the B_s·t values of the magnets rise, the sensitivity of the sensors falls. Compared with an anisotropic MR sensor (MR/Ta/SAL) with the same MR height and track width, an SV sensor is about six times as sensitive, assuming that the resistivity change Δρ for SV is three times as large. The reasons for the higher sensitivity are the larger Δρ, the lower demagnetizing field, and the lower shunting loss, which results from an SV sensor not having a Ta layer or SAL.

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A surface oxidation layer of amorphous Co-Zr-Mo bias film was applied to a 10Å magnetic separation film in a trilayered MR element. Because the surface oxidation layer was thinner than the sputtered film, the bias field saturated at a smaller sense current and the saturation bias field became larger. This paper discusses the state of the surface oxidation. the application of a surface oxidation method to a crystal bias film, and the effect of the process temperature. Oxygen is located at an interatomic position without forming oxide, and a high-density-oxygen area in the bias film becomes nonmagnetism. The surface oxidation method can be applied to both amorphous and crystal bias films. A study of the effect of heat showed that the trilayered MR element is stable at process temperatures up to 240°C.

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This paper describes the read and write performance of thin-film heads using Fe-Ta-N films. Fe-Ta-N films, which show high saturation magnetization and soft magnetism, were prepared by a sputtering method followed by annealing at a temperature of 500°C. The polymer materials (photo resist etc.) used in thin-film heads are normally conventional insulator materials, which have poor heat resistance. We developed a process for fabricating thin-film heads using sputtered SiO₂ films, which have good heat resistance. Thin-film heads using Fe-Ta-N films show good read and write performance on highly coercive media.

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The read-write performances and off-track performances of thin-film heads with NiFe/CoNiFe/NiFe laminated upper poles are studied in comparison with those of a coventional NiFe head and NiFe/CoNiFe laminated heads. NiFe/CoNiFe/NiFe laminated heads with 0.3 μm gaplength have a good overwrite performance equal to that of NiFe/CoNiFe laminated heads with 0.4 μm gap-length. However, the amplitude and PW₅₀ of the isolated pulse are equal to the values for an NiFe head and NiFe/CoNiFe laminated heads with 0.3 μm gap-length Therefore, the effective gap-length becomes wider in a write process, owing to the prevention of magnetic saturation of the inner NiFe film. The effective write-track width of NiFe/CoNiFe/NiFe laminated heads is the same as that of NiFe/CoNiFe laminated heads, because of prevention of head pole tip saturation. Therefore, NiFe/CoNiFe/NiFe laminated heads are suitable for magnetic recording with higher BPI and TPI.

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The write characteristics of thin-film inductive heads in the high-frequency region were examined through R/W testing, recorded bit observation, and dynamic field analysis, and their relations to the pole materials were studied. A thin-film head using a low-resistivity pole, ρ=16 μΩ-cm, could not write data when the frequency was over 40 MHz. Eddy currents in the pole, which cause a phase lag in the recording field to the drive current, were thought to be the reason for this degraded write performance. The amount of the phase lag varied according to the part of the pole, and reached about 5 ns at the track center when the frequency was 20 MHz. Application of a high-resistivity pole material, ρ=90 μΩ-cm, was very effective in decreasing the eddy current loss. In this case, the phase lag of the recording field to the drive current was less than 1 ns at 20 MHz, and data could be written when the frequency was over 90 MHz.

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To achieve high-density recording, it is necessary to develop recording heads that can record on highly coercive media. For this purpose, it is important not only to develop high-B_s materials but also to optimize the parameters of the head yoke.
Three-dimensional magnetic analysis of a thin-film head is therefore examined. This paper discusses the head parameters needed for good recording performance. It also compares the calculation results and experimental overwrite characteristics of a thin-film head with an FeTaN yoke that we developed.

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The surface structure of a thermally cured photoresist (PR) layer used as a thin-film-head insulation layer greatly affects that layer’s insulation resistance (IR) and internal stress. As the carbonyl peak ratio in the PR increases, the IR decreases. In air heat treatment, compressive stress is induced in the PR. These phenomena are explained as follows. Many carbonyl and aromatic ketone groups, which are typical of the hydrophilic group, exist in the PR. Consequently, moisture sorption is induced in the surface of the PR. resulting in swelling of the PR, This stress change is related to the changes in the upper NiFe magnetic domain. It is concluded that suppressing change in the PR surface structure improves the head reliability.

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The response of the magnetic domain structure to an applied field was simulated in soft-magnetic thin films by using a program based on the Monte-Carlo method; this is a new approach in the area of the domain analysis for softmagnetic thin films. A magnetization pattern and a domain structure are formed, so that the free energy becomes minimum. The dipole-dipole energy, the domain wall energy, the anisotropic energy, and the Zeeman energy were considered. Qualitative agreement was obtained between the simulated results and the experimental Bitter patterns.

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A new single-poly-type head with a single-turn thin-film coil is presented. A main pole was laid between two conductive layers of coils to reduce the leakage of magnetic flux from the main pole by means of the eddy current induced in the coils. A ferrite return path core, placed under the lower coil, brought a high read/write sensitivity by shortening the magnetic path in the head. Although only a single-turn coil was used, employment of this scheme with a Co-Cr/Fe-Ni-Nb double-layered medium at a writing current of 50 rnA (0.05 AT_o-p) led to saturation of the medium. A high normalized output of 1000 nV_p-p/μm·turn·m/s was obtained. The recording and reproducing sensitivity was much higher than that of our conventional inductive single-pole head.

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We propose a system for analyzing the magnetic field of a magnetic head, taking account of the residual stress distribution. This simulation system is composed of three analytic parts: a thermal stress distribution analysis part, a permeability distribution analysis part and a magnetic field analysis part. The system was applied to ametal-in-gap-type magnetic head in order to investigate the effect of residual stress on the recording characteristics. We assumed that the stress was caused by the difference in the thermal expansion coefficients of the constituent materials. The permeability reaches a maximum for an optimum combination of thermal expansion coefficients, which are different for ferrite, thin magnetic metal film and bonding glass. The calculated output agrees well with the measured output. Use of the system optimizes the magnetic head in terms of the residual stress.

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In this paper, we use a magnetic circuit method to analyze an electromagnetic shield for reducing the inductance of magnetic heads. First, we constructed a magnetic circuit model of a magnetic head having an electromagnetic shield. The frequency characteristics of the inductance and resistance calculated by using the model agreed with the measured ones. Next, the head inductance and resistance as functions of the shield thickness were analyzed according to the model, and their characteristics were clarified.

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It is well known that the functionability of a magnetic recording system is reduced if a brown stain is generated on the contacting surface of the magnetic head. We investigated how brown stains are generated, by running the magnetic tape in a VTR for several hundred hours. A ferrite head and a metal tape were used as magnetic head and megnetic tape. It was found that generation of a brown stain decreases the wear of the magnetic head, but increases the wear of the magnetic tape. Referring to this result led us to expect that the output deterioration might be avoided if an abrasive operation was applied to the contacting surface of magnetic head and brown stains were not appeared on it. We, therefore, investigated the effect of an AH cleaner, which is a rotating head cleaner containing abrasive particles in a soft materials such as felt. The AH cleaner was found to be effective in preventing the deterioration caused by brown stain.

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The recording noise of sputtered Co alloy media at high recording density was analyzed with readback waveform. It was found that the fluctuation in the magnetic transition region increases with increase in the recording density, and this fluctuation is not random, but is correlated with adjacent magnetic transitions due to intergranular interaction at high recording density.

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The magnetic fluctuation on the rigid disk medium was derived from the medium noise spectrum by using the transfer function of the MR head. The spatial frequency (f_x) dependence of this fluctuation increases in the low and high f_x regions, and shows a similar tendency in both Co₈₆Cr₁₂Ta₂/Cr and Co₇₅Cr₁₃Pt₁₂/Cr media at the density range without interaction of magnetic transition between adjacent transitions. In the dc-demagnetized state, however, the magnetic fluctuation at low f_x is much larger for the CoCrTa/Cr medium than for the CoCrPt/Cr medium. Moreover, MFM observations showed larger magnetic clusters in the CoCrTa/Cr medium. Unlike in the CoCrPt/Cr medium, which has a structure with spatially separated grains, the continuous grain structure in the CoCrTa/Cr medium causes inter-granular effects, and the formation of large magnetic clusters.

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The noise characteristics of obliquely oriented thin-film tapes are investigated with regard to the head-scanning direction. Noise, being less in the normal head-scanning direction than in the reverse-scanning direction, increases in correlation with a demagnetizing action in the higher MMF region. It is inferred that the head field on the trailing side yields AC erasing, functioning more in the reversescanning direction, in which the head field direction almost coincides with the easy axis of the tapes. In the optimum MMF region, the noise increases with the carrier frequency, indicating that the irregularity of the transition region dominates the modulation noise. VSM measurements show that the distribution of the extrinsic eay-axis-direction component of the effective head field on the head trailing side, in which the demagnetizing field is taken into account, exhibits a steeper gradient in normal scanning than in reverse scanning, resulting in a narrower transition width.

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The relation between the magnetic anisotropy field of grains and media noise in vacuum-evaporated Co-O films with oblique anisotropy is studied. The ratio of the coercive force to the magnetic anisotropy field of grains, which indicates the degree of magnetic isolation of the grains. With increasing thickness of the films, the ratio decreases and the media noise increases. The increase of the noise is caused by both the enlarged volume of the films and the weakened magnetic isolation of the grains. Though the degree of the magnetic isolation increases with increasing oxygen content, the media noise increases. It is considered that the increase of the noise is caused by the deterioration of the crystallographic orientation. The degree of magnetic isolation of the grains depends on the grain length. By making the films multilayered, the grain length is kept short and the degree of magnetic isolation of the grains is high.

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The recording characteristics of thin-layer metal particulate media were calculated by a two-dimensional finite element method, using the curling model for the magnetic recording layer. The effects of the maximum flux density and coercive force of the magnetic recording layer, and both in-plane and out-of-plane angular dispersion of magnetic particle orientation, on the reproduced output were calculated. This study reveals the importance of controlling the angular dispersion of the magnetic particle orientations. Although the reproduced voltage increases as the in-plane dispersion is reduced, reducing out-of-plane dispersion often decreases its reproduced voltage. This implies that in a longitudinal metal particulate media, a higher square ratio does not always give higher output. The paper also describes the effects of obliquely oriented metal particulate media on recording characteristics and overwrite efficiency.

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A small quantity nitrogen was added to CoCr thin film during sputtering deposition in order to reduce the inter- granular magnetic interaction. This addition increased the CoCr coercive force (H_c)and reduced the H_c dispersion in CoCr grains. Consequently, the reproduced output and D₅₀ were improved. On the other hand, the media noise caused by magnetic inhomogeneity was also enhanced. This change in the magnetic property is due to the effect of disturbance of the CoCr grain growth by nitrogen addition.

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We developed a three-dimensional magnetic recording simulator that can take account of the effect of magnetostatic interaction in the track width direction. It was used to analyze submicron-track magnetic recording. We studied side writing and cross-talk, comparing their characteristics in perpendicular recoring and longitudinal recording. In perpendicular recording, the side writing was very small, and consequently the effect of cross-talk between neighboring tracks was also very small. The magnetization transition was very sharp. We also showed that in perpendicular recording it is possible to record with a 0.2μm track-width head on a track whose pitch is 0.3μm. In longitudinal recording, on the other hand both the side writing and the effect of cross-talk were large. In addition, the magnetization transition bent significantly on account of the broad recording field of the ring head.

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Au_1-xCo_x (x=0.01-0.94) alloy films were prepared by rf magnetron sputtering onto water-cooled glass substrates. It was found that a non-equilibrium fcc phase appeared in the compositional range of x<0.48. Au-Co non-equilibrium alloy films exhibit Kerr spectra with two peaks at 1.4eV and 3.5 eV. Their spectral shape is completely different from that for the Au/Co multilayered film with nearly the same Co content, which impies Au and Co atoms in sput- tered Au-Co alloy films are mixed each other in atomic scale.

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We studied the magneto-circular dichroism (MCD) spectra of Cd_1-xMn_xTe (0≤x≤1) films and the Mn 3d electronic state by using X-ray photoelectron spectroscopy. A large MCD peak due to the interband magneto-optical transition was observed for 0≤x≤1. The MCD peak height increased monotonically with an increase in x up to x∼0.6, and decreased for x >∼0.6. The photoelectron spectra showed that the p-d hybridization in the valence band was inde- pendent of x. This suggests that the p-d exchange constant is almost constant for all x. The changes in the MCD peak height are discussed in terms of the oscillator strength of the interband optical transition, the magnetization, and the p-d exchange constant. The reason for the decrease in the MCD peak height is the fact that the Zeeman splitting energy is not proportional to the magnetization in the high x region. It is suggested that a high-order perturbation calculation of the Zeeman splitting is important in the high x region.

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Polycrystalline bulk crystals of MnSb were prepared by the normal freezing method, while single crystals of MnSb and bulk crystals of Pt-doped MnSb were prepared by the Bridgman technique. The magneto-optical (MO) spectra of these samples were measured between 1.24 and 6.35 eV. The Kerr rotation spectra of polycrystalline MnSb showed a new peak around 6 eV, which is larger than for lower energies. The spectra of single crystals of MnSb were strongly dependence on their crystal orientation. XRD measurement and an area analysis of EPMA revealed that Pt-doped MnSb grown in the equilibrium condition was characterized by a phase separation into MnSb and PtMnSb. The shape of the MO spectra of Pt-doped MnSb was slightly different from that of undoped MnSb.

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The magnetization and magneto-optical Kerr spectra of ordered MnPt₃ alloy films were investigated. The films were prepared by annealing Mn/Pt multilayers at a temperature of 800°C for 30 minutes. It was found that the MnPt₃ alloy films exhibit very large magneto-optical Kerr rotation, which reaches a maximum value of -1.1 deg at 1.24 eV. It is suggested that the large Kerr rotation is due not to enhancement by plasma resonance but to strong interband transitions.

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Optical magnetic field sensors with high linearity and low harmonic distortion were developed. Bi-substituted rare earth iron garnets were prepared by the LPE method for use as the Faraday rotators of these sensors. The linearity error of the sensor output was obtained within ±1.0% for alternating magnetic fields of up to 300 Oe. The sensor optical system has a new converged beam optical system using ball lenses. The linearity of these sensors is very much better than that of sensors using a collimated beam optical system, on account of the use of graded index (GRIN) lenses. Sensors using GRIN lenses have non-linearity, since only the zeroth-order beam diffracted by garnet maze domains is detected. Sensors using ball lenses have high linearity bacause of the detection of diffracted beams up to the second-order. These experimental results agree well with the calculated results.

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Fine garnet particles of Bi_1.6 Y_1.4 Fe₅ O₁₂ were prepared by coprecipitation and annealing processes for use in the coating of MO films. The conditions of the coprecipitation and annealing were optimized with respect to the magnetooptical properties of the coated films. The annealed Bi-YIG particles were finely ground to about 50 nm in diameter by using a ball mill, and were mixed with cyclohexanone and epoxy binder, and were coated by using a spin coater at 1,000 rpm. A maximum Faraday rotation of ±2° at 520 nm was obtained with the coated film. The prepared MO coated film was used to display a magnetic field pattern.

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Pr-Co alloy thin films were prepared on glass, quartz and single-crystal Si substrates heated at various temperatures by an rf-magnetron sputtering method using composite targets. Pr-Co alloy films deposited on a single-crystal Si substrate heated to 500°C showed a square hysteresis loop with a high coercivity of 5 kOe. On the other hand, films deposited on glass or quartz substrates at room temperature and subsequently heated to 500°C or more showed a mixed hysteresis loop with low and high coercivity.

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In order to improve the magnetic properties of Sm₂Fe₁₇N₃ particles, several milling factors that influence the magnetic properties were systematically examined, including whether the mill is of the vibration or ball type, the milling time and the number of balls. It was found that the _iH_c decreases with aggregates and agglomerates of particles. Strain and oxidation led to a decrease in 4πI_s and 4πI_r. Addition of surfactant in the milling process inhibited aggregates and strain. The magnetic properties of Sm₂Fe₁₇N₃ particles are as follows: 4πI_r = 14.1 kG, _iH_c=9.2 kOe and (BH)_max = 34 MGOe. A typical epoxy-bonded magnet has a (BH)_max of 20 MGOe.

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The microstructures of Sm₂Fe₁₇ alloys heat-treated in hydrogen and subsequently in a vacuum were observed by transmission electron microscopy (TEM). Sm₂Fe₁₇ alloys heat-treated in hydrogen at 600°C for 60 min showed a disproportionate reaction and had a microstructure composed of rod-shaped SmH₂ grains and α-Fe. Hydrogen treatment at high temperature (850°C) caused grain growth, and SmH₂ grains of 20-100 nm in diameter were observed embedded in an α-Fe matrix. Microstructural observations of the alloy heat-treated in a vacuum at 775°C for 5 min revealed the following recombination reaction process: Fe atoms diffuse into SmH₂ grains and react with Sm atoms, resulting in the formation of an Sm₂Fe₁₇ compound. After heat treatment in a vacuum at 775°C for 30 min, the recombination reaction is already complete, and the Sm₂Fe₁₇ grains have grown to a size of 150-300 nm.

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The influence of Nd, B, and other additive compositions on the hard magnetic property of NdFeB alloy powder was studied after mechanical grinding and subsequent heat treatment. The properties are best at 14 and 7-8 atomic percent of the Nd and B compositions, respectively, after mechanical grinding for 24 hours and subsequent heat treatment at 500°C. In V, Zr, and Co, at the optimum magnetic property appears as a result of heat treatment at 600-650°C after mechanical grinding for 24 hours. However, contrary to expectations, Co addition does not improve the property. Addition of 2 atomic percent each of Dy and Pr greatly improves the property, but in the case of Pr, a rapid deterioration occurs after heat treatment at over 600°C. These changes in the magnetic property were investigated by means of X-ray analysis.

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Ternary R₂T₁₇-type alloys Y₂Co₁₇-x-yAlx were studied by means of X-ray diffraction and magnetization measurements.The crystal structures are Th₂Ni₁₇ type for alloys in which 0≤x< 5, and Th₂Zn₁₇-typefor alloys in which 5<x<8. The magnetizations and Curie temperatures decrease with increasing Al content x, and the dependences on x change at 4<x<5. Defects in the cobalt decrease the magnetization and Curie temperature. The nearly linear relation between the magnetization and Curie temperature is discussed in the light of the Stoner model.

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The recrystallization process in Fe_51.2Rh_48.8 thin films was studied to clarify the relationship between the film microstructure and the magnetic transition. It was found that high-temperature annealing results in grain growth and a plate-like structure. The transition temperature and the thermal hysteresis width decrease from 70 to 10°C and from 140 to 3°C, respectively, as the annealing temperature increases from 600 to 1200°C. The film annealed at 1200°C exhibits complete ferromagnetic-to-antiferromagnetic transition as bulk FeRh alloy does. The thin plate-like structure and the lattice distortion strongly affect the thermal hysteresis. It was found that the stress release mechanism is closely related to the thin plate martensitic transformation.

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A deposition process for a rare earth-transition metal (typically a virtual GdCo system) amorphous binary film was studied by means of a molecular-dynamics simulation. The atomic deviation from a site of homogeneous distribution, δ, and the distribution index of an atomic pair ordering, η,were calculated to investigate the atomic structure of the film. The value of δ for the inelastic deformation of the Gd atomic environment was negative and of the order of 10^-4. This indicates that the atoms in the film were stacked more densely in the horizontal plane than in the vertical plane. The value of η showed that the atomic pair was preferentially oriented to the film plane. The magnitude of the perpendicular magnetic anisotropy, estimated from the inelastic deformation of the amorphous alloy thin film, was 10⁵-10⁶ erg/cm³, which agreed with the value obtained by experiment.

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Perovskite-type RE_2/3AE_1/3MnO₃(RE=La, Pr; AE=Ca, Sr, Ba) ceramics were fabricated by a conventional ceramics technique, and their magnetic properties and magnetoresistance effect were measured. The Curie temperatures of all the studied samples were about 77 K, and in particular, that of La_2/3Sr_1/3MnO₃, La_2/3Ba_1/3MnO₃, Pr_2/3Sr_1/3MnO₃ was above room temperature. The typical magnetic properties obtained from the magnetization curves measured at 77 K were M_s≈70-80 emu/g, M_r≈ 10 emu/g, and _iH_c ≈200 Oe.The temperature at which the ρ-T curves reached a maximum was about 50 K lower than their Curie temperature. The MR ratio of each sample was about -20∼-40% in the measurement conditions where T=77 K and H=15 kOe. At room temperature. three kinds of sample whose Curie temperature exceeded room temperature had an MR ratio of about -10%. whereas the rest of the samples had MR ratios of less than - 1%.

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The photo-induced magnetic effect (PME) that the permeability changes in a Co-doped YNdIG single crystal film under the de applied field (H_dc) was measured at 77 K.
Three different states of permeability existed even for the PME measured in a single domain state under the de field. A simple model of the distribution of a-site Co²⁺ before and after irradiation with light suggested that the three different states may be attributed to differences in local magnetic anisotropy and a flopping of Co²⁺ parallel to the external dc field.

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The quantitative relationships between enhancement of magnetization intensity and structural water content in hydrated β''- and β'''-ferrites were studied. The Cd-stabilized Na-β''-ferrite, whose maximun structural water is 3.7 mol/f.u., showed the highest enhancement of the magnetization intensity up to 28.4μWb·m/kg, while the magnetization intensity of K-β''-ferrites was enhanced little by any hydration conditions. It is clear that enhancement of the magnetization intensity of β''-ferrites is directly proportional to the structural water content over 1.5 mol/f.u. in the ion-conductive layer. Enhancement of the magnetization intensity of β'''-ferrites, however, is independent of the structural water content.

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Magnetoresistance (MR) was investigated in Co₂₀Cu₈₀ alloys prepared by the mechanical alloying (MA) method.The crystal structure and magnetic properties of the asmilled and annealed samples were examined for various milling times. After hot pressing at 300°C for 1 h, the MR ratios of samples annealed at 400°C, 430°C, and 450°C for 1 h increased with the milling time. The compact of Co₂₀Cu₈₀ mixture milled for 50 h had an MR ratio of 6.4% when subjected to a field of 15 kOe at room temperature, after annealing at 450°C for 1 h. The annealing time giving the maximum MR ratio became shorter with an increase in the annealing temperature from 400°C to 500°C. The MR ratio of the sample annealed at 450°C for 3 h was 6.7% at room temperature, and did not saturate in a magnetic field of 15 kOe. The content of substituted Co atoms in the fcc Cu lattice phase increased with the milling time. The content of Cu atoms in the hcp Co phase also increased with the milling time, and the hcp phase disappeared after milling times of more than 5 h. The magnetization of the Co₂₀Cu₈₀ mixture decreased with the milling time. Phase separation occurred in both the fcc Cu(Co) phase and the hcp Co(Cu) phase, and the magnetization increased on annling.

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The anisotropic magnetoresistance (AMR) effect of Ni_100-XCo_X (5≤X≤64) single crystals prepared by the bridgman method was studied in the temperature range from 10 K to room temperature. The value of the AMR ratio for the [001] sample of Ni₈₀Co₂₀ reaches about 8.5% at room temperature, and about 68% at 10 K. The composition at which the AMR ratio of the [001] sample exhibits a maximum at 10 K corresponds to that for the magnetostriction constant λ₁₀₀. The mechanism of AMR is discussed on the basis of the model proposed by Berger et al.

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The giant magneto-impedance (GMI) effect is consid- ered for the case of high frequencies, when domain wall motion is strongly damped and magnetization proceeds mainly via the rotation of magnetic moments. The theoretical approach is based on the skin effect in a magnetic conductor with the rotational permeability tensor. In the case of a strong skin effect, the rotational mechanism of GM1 in a transverse magnetic structure is found to result in an impedance change of as much as 100% in magnetic fields of the order of the anisotropy field. The high-frequency response of impedance is generally larger than that associated with the magne- tization via the wall movement. The theoretical results agree satisfactorily with existing experimental data obtained for Co-rich amophous wires and films.

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Magnetic properties were investigated in die-drawn Fe-based, Fe-Co-based, and Co-based amorphous wires (50 μm diameter) that store residual stress caused by mechanical drawing. The characteristic of large Barkhausen dis-continuities (BHD) observed in as-quenched wires was de- stroyed in the die-drawn Fe-based wire but enhanced in the Co-based wire with negative magnetostriction. The BHD of die-drawn Co wire was observed in specimens as short as 8 mm, which are suitable for practical use in sensors. These BHD characteristic changes caused by die-drawing were associated with domain changes caused by magnetostrictive anisotropy. It was observed that the maze and bamboo domains of Fe and Co wire were reversed into bamboo and maze configurations, respectively, by die-drawing. It was also found that die-drawn wires with negative magnetostriction exhibited different domain configurations depending on the amplitude of magnetostriction.

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The anisotropic magnetoresistance (MR) effect, galvano- magnetic electromotive force effect, and forced MR effect in Ni-Fe thin films were studied by using high magnetic fields up to 15 T. These effects were measured in Ni-Fe thin films with various Ni compositions. The quantitative investiga- tion of the anisotropic MR effect and forced MR effect indicated that the dependence of the composition on the characterization of the anisotropic MR effect was similar to that of the forced effect. It was also found that the composition‘s dependence on the characterization of the forced effect had an additional peak around Ni_0.5Fe_0.5,which was not observed in the composition dependence of the anisotropic MR effect.

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