Amorphous Sm-Co magnetic films were prepared by a magnetron sputtering onto glass substrates cooled by water. The sputtering equipment has two targets, above which substrates rotate during sputtering. The composition is controlled by the RF power supplied to each target.
It is shown that the film prepared by this method have planar magnetic anisotropy. The easy axis is along the radius direction of the substrate rotation. This can be interpreted in terms of self-shadowing effect by oblique-incidence sputtering deposition.
The films which have the perpendicular component of magnetization were also prepared under external perpendicular magnetic field. It is shown that this component increases as the strength of magnetic field increases, furthermore, with an electrical field.

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An experimental study of perpendicular magnetic anisotropy and microstructure of Ho-Co sputtered films fabricated at various bias voltages has been carried out. The perpendicular magnetic anisotropy constant K_u is not much changed by negative bias voltage (−V_b). However, a detailed examination of the cross-sectional structure made by high voltage electron microscopy and using a “micro-micro diffraction” technique reveals a strong dependence of film structure on (−V_b). The films made at V_b=0 consist of fine columns of 100 to 200Å diameter surrounded by a network of less dense materials of about 30Å thickness. With increasing (−V_b), a region near one side of film surface, giving rise to a spotty diffraction pattern, appears. With further increasing (−V_b), a highly porous region is found on one side of the film cross-section, but a columnar structure still exists on the other side.
The present result implies that a columnar structure is responsible for the perpendicular magnetic anisotropy for films made at no bias voltage, but other mechanisms must be taken into account for higher bias voltages.

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Compositional dependence of the induced uniaxial magnetic anisotropy constant K_ui was studied for rapidly quenched amorphous (Fe_1-xM_x)₇₇Si₁₀B₁₃, 0 ≤ x ≤ 0.7, (Fe_1-xCo_x)₇₇Si₁₀B₁₃, 0 ≤ x ≤ 1, Fe_100-xB_x, 14 ≤ x ≤ 19 and Co_100-xB_x, 17 ≤ x ≤ 30 alloys. In the former two alloy systems, the results can be explained by taking into account (i) insertion of metalloid atoms between ferromagnetic atoms and (ii) the directional ordering of magnetic atoms. While in the latter two binary alloy systems, the compositional dependence of K_ui can be explained roughly by (i).

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Since the propagation properties of magnetoelastic wave (MEW) in amorphous magneto-strictive ribbons and/or films depend on the magnitude and the direction of the in-plane uniaxial anisotropy, control of the anisotropy is considered to be of essential importance to produce reliable and prominent magneto-acoustic transducers. We have examined the effect of thermal treatment on the delay time properties of MEW in (Fe, Ni) base rapid quenched ribbons with large magnetostriction (λ_s ≅ 30ppm), where annealing was performed by applying a transverse magnetic field of 700 Oe and a longitudinal tensile strain. Although the experimental results are rather complicated, it is found that the optimal annealing condition which exhibits the maximum change in delay time due to external magnetic field exists.

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Magnetoresistive effect of NiCo films prepared by r.f. diode sputtering was investigated for the application upon magnetic sensors and magnetic thin film heads (MR heads).
The sputtered films without heat treatment may be characterized by small value (≤1.1%) of magnetoresistive effect due to its small value of Δρ and high electrical resistivity ρ. It was found that annealing in hydrogen is substantially effective to reduce the oxide and to bring the grain growth in films, and it results in large value of magnetoresistive effect because of decreased value of ρ and increased value of Δρ. The films of which Ni concentration is in range 60 to 80 weight percent showed 4.5 ∼ 5.3% of magnetoresistive effect as a result of annealing in hydrogen at 400°C for 60 min.

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The magnetic properties of sputtered iron oxide films have been studied. Fe₃O₄ films were directly formed by reactive sputtering of an Fe target in Ar-O₂ atmosphere, and were annealed in a temperature range from 265 to 345°C.
Coercive force H_c of the films at low temperatures increased with increasing annealing temperature, though the decrease in coercivity was reported for powder specimens. The values of H_c and M_r/M_s, were also affected by crystallite orientation of the films. The relation between H_c and structure of the films was discussed.

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Magnetic anisotropy changes due to He⁺ ion implantation into (110) oriented garnet films have been studied. The induced magnetic anisotropy changes, which were measured by ferromagnetic resonance, are related to the two magnetostriction coefficients, λ₁₀₀ and λ₁₁₁, and also to the degree of suppression of growth induced anisotropy. The two kinds of (110) Eu₃Fe₅O₁₂ films, with and without growth induced anisotropy, were studied in detail from the viewpoint of implantation damage level. For small damage level, the implantation induced change of orthorhombic anisotropy parameters A and B agrees for both films with and without growth induced anisotropy. However, there are clearly significant differences between the both films for heavier damage levels. He⁺ ion implantation effects were also investigated for various garnet compositions, such as YSmLuBiCaGe, YTmBiGa, GdSmTmCaGe, etc.

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A simple mechanical device, or model, has been constructed for the rapid simulation of magnetic bubble domain current-sheet devices. The device consists of a small ferrite magnet (5 mmφ), layers of perforated aluminum films whose sizes match the diameter of the magnet, and a drive-current generator composed of standard TTL packages and relays. The magnet is placed in a light plastic boat, which is floated on the surface of a viscous fluid. The current generator provides sequenced electric currents with amplitude ranging between 1 and 10 A and duration between 1 and 30 s. The device has been applied to implement dynamic reallocation loops in dual perforated current-sheets, and several loop configurations, all operational on the mechanical model, have resulted. The course of improvement leading to the final loop configurations is given together with the result of preliminary experiment showing the validity of the model.

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Garnet LPE films containing bismuth which support 1 μm bubbles have been grown on (111) GGG substrates. Gallium substituted garnets, such as YSmTmBiGa, YTmBiGa and LaSmLuGa films, have good properties at room temperature, e.g., low damping, small collapse field (H_co1) and small crystalline anisotropy constant (|K₁|). These films are not suitable for bubble propagation at higher temperatures because of too low Curie temperature (T_c) after ion implantation. On the other hand, calcium germanium substituted garnets, such as GdSmTmBiCaGe and YSmTmBiCaGe have higher T_c and larger negative magnetostriction coefficient, λ₁₁₁. However, Q factor or characteristic length (l) is restricted by small Sm³⁺ contents in these films. By substituting Si⁴⁺, instead of Ge⁴⁺, we can get much room to adjust the film properties. GdSmLuBiCaSi films have zero temperature dependence of H_co1. Temperature coefficient of H_co1 for YGdSmLuBiCaSi is −0.2%/°C Atomic compositions for BiCaSi substituted films are analyzed. Y³⁺ and Lu³⁺ are partially substituted into a-site. Distribution coefficients for Y³⁺, Gd³⁺, Sm³⁺ and Lu³⁺ are estimated.

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New bubble garnet films with orthorhombic anisotropy, (YTmGdBi)₃(FeGa)₅O₁₂, (YTmEuBi)₃(FeGa)₅O₁₂, (YTmSmBi)₃(FeGa)₅O₁₂ and (YTmLaBi)₃(FeGa)₅O₁₂, have been epitaxially grown on (110) GGG substrates. Although a large in-plane anisotropy K_p of 2∼4×10⁴ erg/cm³ is induced in YTmEu and YTmSm films, the uniaxial anisotropy K_u obtained is not large enough to be used for bubble materials. In YTmGd and YTmLa films, K_u is of almost the same magnitude as K_p with a value of 1.0∼1.5×10⁴ erg/cm³. The wall dynamics has been investigated by stripe domain transport method. For YTmLa films, the wall mobility μ is ∼22 m/sOe, the peak velocity V_p is ∼120 m/s and the coercive force H_c is ∼0.7Oe. These characteristics may be useful for current access devices.

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Co_1-xPt_x(x=0−0.60) thin films prepared by r.f. diode sputtering have been described as a new material for high density longituginal recording medium, which does not need a thick overcoat as a plated Co-Ni-P thin film and which has higher remanent flux density than ferrite thin film, having excellent corrosion resistivity and magnetic properties. The maximum H_c value is obtained at around 20 at. % Pt. Magnetic characteristics, such as H_c, B_s and squareness, of Co_0.80Pt_0.20 film are 1,100 Oe, 12,000 G and 0.90 respectively at 1,000 Å thickness. These values are not changed over 1∼15 Watt/cm² power density corresponding to 58∼850 Å/min. The films, more than 28at. % Pt, have no Bs change after immersion in water for over one month. Ni additive effects in Co-Pt films on magnetic properties and corrosion-resistivity are also described.
Further, 51,000 FRPI linear recording density was obtained, as D₅₀, using a Co_0.70Ni_0.10Pt_0.20 thin film disc and a 0.46 μm gap length head at 0.12 μm head-medium spacing.

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Magnetic annealing treatments were applied to Co doped ferrite thin film media on heat- resistant flexible substrates, which were deposited through a process including direct formation of Fe₃O₄ films by sputtering sintered targets of Co doped Fe₃O₄.
Conditions to achieve the best effects of the treatment were invstigated to be a static magnetic field greater than 1 kOe and cooling-start temperature above 150°C. Under such optimum conditions, squareness S and coercive squareness S* increased to 0.8 and 0.9, respectively, coercive force Hc also increased and pressure demagnetization decreased markedly to 3∼4%.
It has been revealed that, through the treatment, uniaxial magnetic anisotropy Ku (3 × 10⁴∼2 × 10⁵ erg/cc) was induced parallel to the applied magnetic field.
The induced uniaxial magnetic anisotropy, whose origin is considered to be the same as bulk cobalt ferrites, improves magnetic properties, stabilizes the magnetization and thus decreases the pressure demagnetization.

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A new Hall magnetic head for digital reading has been manufactured using evaporated GdFe amorphous thin films which show far larger sensitivity for the magnetic field applied in a certain direction along the film plane than the field along the film normal. The Hall head has the following features; 1) strong directivity to field, 2) high sensitivity (product sensitivity K_H=73 mV/mA · kOe), 3) puls-like output with a constant value, 4) good performance in high-frequency field (from DC to at least 100kHz).

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Permeabilities, hysteresis loops and domain patterns of sputtered permalloy films which have various magnetostriction constants were studied. The films were striped, stepped and finally coated by sputtered Alumina films. The magnetic characteristics of these films were different from that of the sheeted films. The experimental results can be explained by the induced uniaxial stresses of the films for each shape. The magnetostriction con-stant is an important magnetic property of the permalloy film for thin film heads.

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The effects of magnetic properties and thickness of Co-Cr/Ni-Fe double-layered medium on perpendicular magnetic recording are investigated. Experiments are performed using a single-pole-type head for recording and a ring-type head for reproducing. Our experiments show that: (1) Thickness of the Ni-Fe layer is required to be greater than half of thickness of the head pole to obtain the maximum reproduced voltage. (2) Reproduced voltage E_p is proportional H_c^0.6 (H_c: coercive force of the Co-Cr layer in the film normal direction). (3) E_p/H_c^0.6 to (≡E_p′) is independent of saturation magnetization of the Co-Cr layer. (4) E_p′ increases with thickness of the Co-Cr layer δ_p at long recording wavelength. (5) E_p′ is independentof δ_p when the recording wavelength is short. The relationships (2) to (4) are close to those suggested by calculation based on magnetization model of the medium and a reciprocal theorem. But the relationship (5) a does not agree with the result of our calculation probably because of the incorrectness of the magnetization model for short recording wavelength. The calculation shows that magnetic interaction between the ring head and the medium has an important effect on the reproducing characteristics.

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This paper describes a new half-tone recording method in magnetography by utilizing the demagnetizing effect in short wave length recording. As the spatial frequency of recorded transition regions increases, the strength of magnetization decreases. Since the magnetic force, which attracts magnetic toners, depends on the strength of magnetization at the transition regions, the quantity of attracted magnetic toners depends on the spatial frequency of the transition regions.
A recording current of a low frequency was applied to a recording head for a video signal which represents a black image. The currents of higher frequencies were applied in accordance with changing of video signals from black to white. In order to realize a white image, either the current of the highest frequency, which exceeded a predetemined frequency, or the direct current was available.
A developed image was established by the facts that more toners were attracted in the areas between the transition regions with low spatial frequency and less toners with higher spatial frequency.
A produced copy has half-tone images whose reflective density ranges from the value over 1.4 to about 0.2.

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Amorphous TbFe films have been prepared by EB evaporation technique on glass substrates. After preparing TbFe films of about 220 Å in thickness, SiO_x and the reflective layer (for example Au, Ag) were deposited without breaking vacuum.
The reflectivity, the minimum writing laser power and effective Kerr rotation angle of this structure were measured as a function of SiO_x film thickness and compared with the respective values of a film without reflective layer. The thickness of TbFe and SiO_x layers for minimum writing laser power and maximum effective Kerr rotation angle was determined. Using this optimum structure, a carrier-to-noise ratio (C/N) of 44 dB at 2.048 Mb/s (NRZ) was obtained, which is a few dB larger than that of TbFe mono-layer films.

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An optical gaussmeter is proposed to detect an internal fault of a power transformer: when a turn short circuit occurs, the stray flux pattern changes from a symmetrical to an asymmetrical pattern.
The gauss meter uses a beam-guide type Faraday rotators as the field sensor and optical fibers as the transmission line. A laser beam travels through the Faraday rotators along multiple passes which are slightly canted from the leakage field, so that the field sensitivity of the rotators becomes very high. The minimum detectable leakage field is 1 G for 50 Hz. Analytical calculations as well as some experimental measurements are carried out to detect the position of an internal fault of a transformer.

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Some rare earth-transition metal amorphous alloy films prepared by sputtering or evaporation have uniaxial anisotropy perpendicular to the film plane. These amorphous magnetic films are expected as magneto-optical memory material. Although amorphous TbFe magnetic film has a high coercivity and low Curie temperature, the signal level of magneto-optical readout is lower than other amorphous magnetic films. Therefore the higher magneto-optic properties (higher Kerr rotation angle) is desired.
For obtaining a higher Kerr rotation angle, amorphous TbFeCo films was studied. It is found that the suitable Co substitution for Fe caused the increase of the Kerr rotation angle of amorphous TbFeCo magnetic films and θk at 633 nm and 840 nm have peak values 0.42° and 0.52° at X=50 in Tb₂₁(Fe_100-XCo_X)₇₉, respectively.
Curie temperature of TbFeCo increased linearly with increasing Co concentration and its slope was about 3.6-4 degree.
From the temperature dependence of the Kerr rotation angle it is conjectured that, in Tb₂₁(Fe_100-XCo_X)₇₉, the transition metal magnetic moment at 0 k becomes a maximum at near X=30 as well as a maximum saturation magnetization in FeCo binary alloy.

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Kerr and Faraday effects in CoCrFe₄ films have been measured at λ=0.4−0.9 μm. The films RF-sputter deposited on both quartz glass and Si-wafer substrates. They are about 0.31 μm in thickness and polycrystalline with no preferred orientation. The easy axis of magnetization is directed in plane of the film. The Kerr effect of the film does not show large normal remanence and high coercivity, which differs from the Kerr effect RCD of bulk samples. Since the film is transparent, Faraday rotation θ_F superposes Kerr rotation θ_K. Introducing term of ‘effective reflectivity’, the wavelength dependence of the rotation angle θ is consisa tently explained in various experimental configurations.
Figure of merit for θ_F takes peak values of 2θ_F/α=1° and 3° at λ=0.62 and 0.71 μm, respectively. Figure of merit for θ (containing θ_K and θ_F in a comparable degree) takes maximum value of 2Rθ=0.6° at λ=0.72 μm. These peak values are ascribed to the crystal field transition of the tetrahedrally coordinated Co²⁺.

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(YNd)₃Fe₅O₁₂ films with in-plane magnetization for magnetooptical waveguides were grown by liquid phase epitaxy. Precise control of lattice mismatch which is necessary for phase matching between TE and TM modes was achieved by utilizing temperature and growth rate dependences of Pb ions incorporation into the film from PbO in the melt. Small amount of Nd³⁺ ion substitution (2 mole %) was sufficient for obtaining the film with in-plane magnetization. High power conversion ratio (79%) was obtained. It was found that the growth temperature change of the observed birefringence is several times larger than that calculated from the lattice mismatch and the magnitude of the birefringence can be reduced by thermal annealing.

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A Fabry-Perot resonance (F.P.R.) type Faraday rotator which consists of a magneto-optic medium with mirror coating at the ends has been made. The Faraday rotation of the medium is enhanced (1+Re^-αl)/(1−Re^-αl) times (R: reflectivity of the mirror, e^-αl: optical loss of the medium) under F.P.R. condition. As a theory predicts, the Faraday rotations of the rotators using Pyrex glass and GGG with silver coating of R=0.83 and 0.9 were enhanced 10 and 20 times, respectively, while, when the rotator using LPE-garnet film with silver coating of R=0.8 was used, the enhancement was limited to 3 times. The difference comes from the effect of the optical absorption e^-αl.

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A new DC-AC converter for local energy utilization system is proposed in this paper. The DC-AC converter is constructed with orthogonal cores and a three-phase thyristor inverter. Using the DC-AC converter, we can easily supply the power from a DC power source to an AC distribution line. The DC-AC converter exhibits following features:
(1) The isolation between the DC power source and the AC distribution line is good. (2) The power can be transferred from the DC power source to the AC distribution line over the wide DC voltage range of the input. (3) The DC-AC converter has simple construction and the maintenance is easy.
The DC-AC converter presented here is useful for utilizing small powers such as the power generated by solar cells.

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A new static magnetic shielding equipment consisted of several U shaped soft ferromagnetic bodies is proposed. This magnetic shielding equipment shows a remarkable shielding effect and the shielding factor can be adjusted optionally. Magnetization characteristics of the U shaped soft ferromagnetic body in a uniform magnetic field are analized by a numerical method assuming that magnetization of a short segment of the U shaped soft ferromagnetic body is uniform over the short segment. The shielding effectiveness is calculated by superposing a demagnetizing field due to magnetization of the U shaped ferromagnetic body on an external field. The calculated results are in very good agreement with the measured results.

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Accurate and quick response type magnetometers are presented using two amorphous core multivibrator bridge with a dc output. As-prepared zero-magnetostrictive amorphous ribbons of Fe_4.7Co_70.3B₁₅Si₁₀ with 1-mm width are used as straight form for field sensing. In these two core type magnetometers, sensitivity is about 8 times that of one core type magnetometers and temperature stability and flux change stability are high due to that the flux reversals occur in rotational magnetization regions. Minimum detectable field is about 10^-5 Oe and the cut-off frequency for ac field detection is about 3 kHz. Analytical results are compared with the experimental results.

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This paper describes a method for obtaining the performance characteristics of a parametric induction motor and its application to a high speed motor. Following items are clarified:
(1) The output characteristics of the motor can be calculated using a modified equivalent circuit of an asymmetric two phase induction motor.
(2) The motor has suitable features for high speed rotation because of simple structure and two poles machines.

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A new linear motor utilizing the parametric oscillation has been proposed. This linear motor has many features follows: (a) No slot and simple in structure, (b) Low cost and mass-production, (c) A unit-type in shape and the variety of the path with the arrangement of the units.
The value of F/P₁ (the ratio of force to input power) of the motor made for trial was about 1/3 times larger than that of usual ones. But it will increase by considering the optimum design.
Because of these features this linear motor will be applied to many kinds of machines which need the linear force.

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To confirm the utility of high gradient magnetic separation (HGMS) for the beneficiation of rare earth ores, a model experiment is made recover the magnetic Nd₂O₃ particles from water slurries containing Nd₂O₃ and CaCo₃ particles, where each component is made up the magnetically simulated element for representative rare earth ores such as Bastnasite and Monazite.
The initial recovery reaches more than 80% with the use of commercial HGMS filters and the application of moderate magnetic fields (≅5 kOe). The concentration of mags or the grade is increased by a factor of more than 10. The decrease of the recovery due to the loading of mags in the filter is remarkable in the case of parallel stream type filters, but the tendency is found to be considerably improved by the use of a dispersant of about 0.1% in concentration.

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The magnetic phase diagram was determined for amorphous (Fe_1-xNi_x)₇₇Si₁₀B₁₃, 0.8≤x≤1, alloys by measuring the temperature dependence of ac susceptibility χ_ac. The magnetic field dependence of χ_ac was studied for an amorphous (Fe_0.1Ni_0.9)₇₇Si₁₀B₁₃ alloy to clarify the origin of the inflection in χ_ac-T curve observed at low temperatures. The field dependence of χ_ac was analyzed into linear susceptibility χ₀ and nonlinear susceptibility χ₂. The value of χ₀ and χ₂ exhibited an inflection and a peak at T_f, respectively. The physical properties such as saturation magnetization, magnetic anisotropy and electrical resistivity changed smoothly at T_f while the coercive force began to increase at T_f with decreasing temperature. The origin of the inflection in χ_ac-T curve at T_f was discussed by taking into account the increase of the magnetic anisotropy of the assumed magnetic clusters.

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Crystallographic examination, domain observation and the process of magnetization reversal in single crystals of Sm₂Co₇, SmCo₅ and Sm₂Co₁₇ were studied. Nucleation field H_n in SmCo₅ and Sm₂Co₇ varies with premagnetizing field H_ex and this dependence of H_n on H_ex saturates at values of H_ex above 15 kOe.
Furthermore, it is found that the nucleation field H_n depends on the surface condition and the size of the single crystal sphere.

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By rapid quenching techiques directly from the liquid, Sm-Co binary ribbons were produced over the range 20∼39wt% Sm. The samples were melted and quenched in Ar gas atomosphere in order to avoid oxidation. The continuous ribbons obtained were 20 to 50 μm in thickness, 1 to 3 mm in width and about 1 m in length. These ribbons were flexible, and it was possible to wind around a rod 8 mm in diameter. The coercivities of as-quenched Sm-Co ribbons for Sm content > 34 wt% (the stoichiometric content of SmCo₅) were almost the same as the sintered SmCo₅ magnets. In the case of Sm content < 34 wt%, the coercivities of Sm-Co ribbons were higher than those of sintered Sm-Co systems.

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Very hard and very spherical ferromagnetic particles are prepared using a rapid quenching technique on a rotating disk. Glossy spherical particles with 10-300 μm diameter and Vickers hardness of 970-1100 are produced by ejecting melts of Fe_81-xCr_xB₁₇Si₂ (1≤x≤10) in a quarts tube through a 0.35 mm diameter nozzle onto a point of a rotating disk surface, the surface speed at which is 10-13 m/sec. The saturation flux density and the coercive force are 14.5 kG and 34 Oe for x=1, and 10 kG and 100 Oe for x=10. Temperature characteristics of B_s for 1≤x≤10 show three phases of microcrystalline ferromagnetic materials. Grain sizes in particles are estimated as less than 0.1 μm using SEM observations and X-ray diffraction patterns.

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