MR (Magnetoresistance) charateristics of metallic multilayers such as [M/X(M'/X)] and spinvalve multilayers such as [{Fe-Mn/M/X/M}/X] were studied, where M=Ni-Fe-Co, Co-Fe, … and X=Cu. [Ni-Fe-Co/Cu(/Co/Cu)] showed considerably large MR ratios and small saturation fields, and are suitable for MR sensors. [{Fe-Mn/Ni-Fe-Co/Cu/Ni-Fe-Co}/Cu] showed sharp and very small switching fields and are suitable for low field operations. Thermal stabilities of these multilayers were studied and the films having Co/ Cu interfaces were found to be more stable than those having Ni/Cu interface. MR characteristics of MBE grown epitaxial multilayers and CPP (Current Perpendicular to the Plane) MR were also discussed.

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Magnetoresitive properties were investigated for Co₉Fe/Cu/Co₉Fe sandwiches with a 21A Cu layer thickness and different Co₉Fe layer thicknesses which were prepared on a MgO (110) substrate using ion beam sputter deposition. The influence of a 50A Fe buffer was also investigated. In-plane uniaxial magnetic anisotropy (K_u) in addition to cubic anisotropy (K₁) was induced, of which the easy axis was along MgO (001) and MgO [110] without and with a 50A Fe buffer layer, respectively. The magnetoresitance (MR) ratio monotonically decreased with increasing Co₉Fe layer thickness in the investigated thickness range of 25 to 70A. The maximum value obtained was 11.5% at room temperature. With increasing field the MR saturated with a gentle slope after a steep drop at a small field without an Fe buffer layer, but rapidly saturated at a small field with an Fe buffer. These behaviours can be understood by magnetization processes taking into account both K_u and K₁.

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For the practical application of nano-crystalline Fe-based nitride (Fe-Ta-N) films to magnetic heads, a new sputtering method has been developed, and magnetic anisotropy of Fe-Ta-N films (Ta: 10.5-11 at%, N: 11.5-14.5 at%, bal. Fe) prepared at substrate positions of large area was investigated in detail with mass production of the films in mind. The anisotropy direction of the films with low N concentration (11.5 at%) annealed without magnetic field changes with the substrate position, but the anisotropy of the films with high N concentration is in the same direction at all substrate positions. With increasing N concentration, anisotropy field increases and permeability is improved at high frequencies.
The direction of the in-plane magnetic anisotropy of the films fabricated with an RF bias applied to the substrate rotate 90° from that of the films prepared without a bias. The sputtering process using the substratebias method makes possible mass production of FeTaN/SiO₂ multilayer films having isotropic high permeability at high frequencies.

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Nanocrystalline Fe-Hf-C films crystallized from amorphous state are known as a soft magnetic material with high saturation magnetization. The grain growth is suppressed by Hf-carbide particles finely dispersed at the grain boundaries of bcc Fe, resulting in high thermal stability of nanocrystalline state. However, these non-magnetic carbide particles reduce the bcc-bcc grain boundary region which plays an important role for the intergranular exchange interaction, reducing the effective magnetocrystalline anisotropy.
In this paper, the improvement of their soft magnetic properties was described. By a Si addition, the concentration of Hf and C (i. e. the non-magnetic carbide particles) was successfully reduced to less than the half of that needed for the ternary Fe-Hf-C films. These films with reduced Hf-carbide concentration showed low coercivity and improved anisotropy dispersion in spite of the increased grain size of bcc phase. This is most likely caused by the enhancement of the intergranular exchange coupling. These improved films also exhibited high saturation magnetization of 1.6 T as well as improved high frequency permeability and low magnetostriction suitable for magnetic heads for high density recording.

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Stripe amorphous film which has closure domain stracture has been investigated to clarify effect of induced magnetic anisotropy on stabilization of domain wall. The aging temperature is fixed at 150°C in order to expose speciments to the same temperature of fabrication process as magnetic head. The decrease of initial permeability and change of B-H curves after aging are observed. These phenomena can be interpreted in terms of the stabilization of the domain wall by locally induced magnetic anisotropy. The elevation of pre-annealing terperature higher than 350°C is effective to maintain soft magnetic properties of stripe and thin film head.

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Galvanomagnetic effect in ferromagnetic thin films is widely utilized for magnetoresistive devices. Especially, magnetoresistance (MR) effect attracts much attention in use of the sensors and readout heads. Galvanomagnetic electromotive force (GEMF) effect, which has been called planar Hall effect, is also observed in magnetic films. These two effect are originated from a same phenomenon, where the electromotive force is generated by interactions between conduction electrons and magnetic field. Although the fact, the characteristic of MR and GEMF effects are different. This is because that MR effect is observed along the current direction, whereas that GEMF effect is observed perpendicular to the current. In this paper, MR and GEMF is studied in view point of the differences of their characterization.

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Co-Zr-Ta-Nb amorphous films with thickness 1-3μm were fabricated on polyimide sheets. Thermal changes of the corecive forces and the uniaxial anisotropy field were investigated in order to obtain the optimum annealing conditions for improvement of the magnetic softness. The films were found to exhibit good magnetic softness comparable to those on glass substrates. Based on those results the sheets were wound on an alumina bobbin and after annealing in a D. C. or a rotating field, initial permeability (μi), hysteresis loss (Wh), core loss (Wc), eddy-current loss (We), effective permeability (μe) and corecive force (Hc) were measured. A core with film thickness of 3μm exhibited core loss less than that of supermalloy cores (thickness 5μm) for Bm=0.1T. Effects of annealing and change of the film thickness on μi, Wh, Wc, We, μe and Hc are discussed.

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T. K. Kim and M. Takahashi have found that iron nitride thin films of α"-Fe₁₆N₂ have the saturation magnetization Ms more than that of 30at%Co-70at%Fe alloy in 1972. Two of the authors have described that the saturation magnetization Ms of polycrystalline iron thin films increased approximately 21% after the thin films were nitrided by the magnetron discharge method.
In this paper, the authors have studied the magnetic property of polycrystalline iron foils treated by the magnetron discharge method. The experimental results obtained are summarized as follows:
The surface temperature of iron foil became about 205°C with magnetron discharge method under an N₂ gas pressure of 4.0×10^-2Torr. α"-Fe₁₆N₂ and/or α'-nitrogen martensite, γ'-Fe4N, and α-Fe phases are detected by the X-ray diffraction method in foils nitrided under various N₂ gas pressures. The rate of increase of Ms is 3.2% after the iron foil was nitrided under an N₂ gas pressure of 4.5×10^-2Torr. The saturation magnetizations Ms of α"-Fe₁₆N₂ and/or α'-nitrogen martensite, calculated by using X-ray integrated intensity ratios, are 222-245emu/g in foils nitrided under various N₂ gas pressures.

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Magnetoresistance has been investigated for nanogranular Cu_100-xCo_x sputtered films and liquid-quenched ribbons. Solid solutions were obtained in a wide concentration for sputtered films and in a concentration with x<15 for the liquid-quenched ribbons. Nanostructured magnetic precipitates, whose size was evaluated by small angle neutron scattering, in Cu-rich matrix were evolved by subsequent aging. The giant magnetoresistance (GMR) was observed in the aged nanogranular alloys. The largest differential MR ratio of 4%/kOe was obtained in Cu₇₀Co₃₀ film aged at 500°C for 1h.

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Magnetic properties are reported for Fe/FeCoZr multilayer films prepared by rf magnetron sputtering method. The multilayers have a bcc structure with the (110) preferred orientation and consist of fine crystallites of about 10 run in diameter. Saturation magnedzation (Ms), saturation magnetostriction constant (λs), coercive force (Hc) and permeability (μ) of the multilayers were examined with varing the composition of the FeCoZr layers. In Fe/Fe_38.9 Co_40.1 Zr₂₁ multilayer, Ms=2T, Hc=40A/m and λs<1×10-6 were obtained after annealing at 300°C. This film also exhibited high pemleability of about 2800 at frequencies up to 200 MHz.

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Frequency dependence of complex permeability was investigated in soft magnetic films. In this paper, in order to examine the magnetic losses in high frequency, we investigated the frequency dependence of the real and imaginary components of permeability (μ' and μ") and loss tangent (tanδ=μ"/μ') at 1000MHz. Strip type and square type double layer CoNbZr/SiO₂ films and multilayer CoFeSiB/SiO₂ films are prepared by RF sputtering machine and lift-off method. Strip type double layer film with 300μm width shows low losses. Multilayer films were fabricated with various CoFeSiB and SiO₂ thickness and number of magnetic layer. High frequency losses of macro size (10×20mm) films are compeared with that of micro size (1×2mm) films under the total magnetic thickness of 2μm. It is found that micro size multilayer film shows 1/tanδ=70 at 100MHz for CoFeSiB (0.1μm/)/SiO₂(0.05μm). The present results emphasize that magnetic losses in high frequency should be taken into account magnetic core size when we use magnetic film in micro device.

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Polyamideimide (PAI) composite films containing glass were prepared by Sol-Gel process. The dielectric breakdown of the composite films with and without silane coupling agent (SCA) and PAI films was studied by taking an advantage of self-healing. The dielectric strength E_b of the composite films with SCA is nearly equal to that of the PAI films, but differs from that of the composite film without SCA. This is caused by the difference of the interface between glass and PAI. E_b is lowered by aging at 300°C, Eb of the composite film with SCA being decreased more sharply than those of the other films. The decrease in Eb seems to be caused by oxidation of SCA as well as diphenylmethane groups in PAI chain. Although SCA contributes minimize the defect of the interface, it bring about the additional oxidation for heavy thermal aging.

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The electrical properties of glow discharges in Ne and Ar gas mixtures have been analysed. The electric field as a function of the electric current in the positive column has been measured and also calculated by a diffusion equation method. The electron swarm parameters used in the present calculation have been deduced by a Boltzmann equation method. The result shows that the calculated variation of the electric field vs the current is good agreement with the measurement.
It is found that the minimum value of the electric field appeares at the Ar partial pressure around 1% at a fixed current. A qualitative explanation for this fact may be made by that the electron energy distribution of 1% Ar and 99% Ne at high elctron energy is larger than that of pure Ar and the Penning ionization.

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