Has been required, but the most effective countermeasure to the noise of electrical machinery has not yet been devised. The main factor causing the noise and vibration in the composed transformer is magnetostriction. The magnetostriction is very sensitive to stress and heat.
This paper deals with a formulation for analysis of the magnetostriction on external load by the finite element method. Analysis is made of the magnetostriction induced in a one dimensional model by stress and magnetic flux density.

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In Fe-Zn alloys obtained by rf sputtering technique, a single bcc phase is extended up to about 60at % Zn. The metastable bcc phase is ferromagnetic at low temperatures. The average magnetic moment decreases with increasing Zn concentration and deviates slightly upwards from the simple dilution law. An increase in the magnetic moment of Fe atoms is probably due to the volume expansion of Fe atoms by the substitution of larger Zn atoms. Their Mössbauer spectra show a very broad ferromagnetic sextet.

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Pure Fe films produced by γf sputtering under several Ar gas pressures have been investigated by X-ray diffraction, SEM, VSM and the Mössbauer effect. In the Mössbauer spectra, a perpendicular magnetic anisotropy was observed for films made under high Ar gas pressures, while an in-plane anisotropy was seen for films made under low Ar gas pressures. Since the magnetic moments of the films made under high Ar gas pressures turn to the films plane in a low field, the pure Fe films are not suitable for perpendicular magnetic recording media.

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A series of compositionally modulated Nd-Co thin films was prepared by UHV evaporation. The modulated structure and composition of the films were studied by X-ray diffraction measurement and energy dispersive X-ray microanalysis, respectively. Magnetization and anisotropy measurements were carried out using a vibrating sample magnetometer in the temperature range between 77 K and room temperature. A coherent structure was found over the modulation length, Λ, range 20 Å ≤ Λ ≤ 70 Å. The magnetization of the films with an atomic ratio of Nd : Co=1 : 3 changed slightly with Λ, but the perpendicular anisotropy energy decreased significantly with increasing Λ. The reduction of the anisotropy energy seems to be due to a decrease in the amount of atoms which are adjacent to the interfaces between Nd and Co layers.

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Multilayered films are prepared by the alternate deposition of Mn and Sb in ultrahigh vacuum. On deposition, Mn atoms react with Sb atoms to form a ferromagnetic compound MnSb at the interface. The MnSb layers grow epitaxially on thick Sb layers. By utilizing this epitaxy, ultrathin (less than 10Å) MnSb layers are sandwiched between thick (50Å) Sb layers. The resulting superlattice films are ferromagnetic even when each MnSb layer thickness is less than 5Å.

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Multilayered structures and magnetic properties were studied for multilayered Fe/Cu films prepared by rf-magnetron sputtering method. Thickness of each Fe and Cu layer was 2.5, 5.0, and 10 nm, and the total thickness of Fe layers was 100 nm. When the thickness of Fe and Cu layers was less than 5 nm, Cu-K_α X-ray diffraction patterns showed one reflection at 2θ=44.1 degrees, which was intermediate between bcc Fe (110) and fcc Cu (111). Auger electron spectroscopy analysis and transmission electron microscopy (TEM) observation of a cross-section of these films showed periodic multilayered structure. The magnetic anistropy in the plane of multilayered Fe/Cu films was more remarkable than that of 100 nm Fe single layer film, and the coercivity decreased as thickness of the Fe and Cu layers decreased.

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Magnetic and magneto-optical properties of amorphous Zr-Fe/Tb-Fe composition modulated multilayered films (CMF) prepared by RF sputtering technique were investigated. In this system, a composition modulation period (D) more than 40 Å was confirmed by the low angle X-ray diffraction method. Curie temperature (T_c) of these multilayered films falls with decreasing D, but saturation magnetization (M_s) and perpendicular anisotropy (K_u⊥) increase with decreasing D. Sharpening of hyperfine field distribution was observed with the decrease of D. Wavelength dependences of magneto-optical Kerr rotation (θ_K) are independent of the variation of D.

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Magnetoresistive effect, effective anisotropy field, domain patterns and reading abilities were studied in improved type sensors made of high magnetoresistive Ni-Co films with auxiliary pole of Ni-Fe films. Demagnetizing field in improved type sensors with the same Ni-Co stripe width as conventional type sensors was reduced to half that of the latter. Under an angular change of applied field or an application of low bias field, magnetoresistive effect in conventional type sensors decreased. This was caused by the existence of domain walls. On the other hand, improved type sensors were composed of a single domain; therefore, magnetoresistive effect did not decrease under the same field conditions. Read-out value for magnetoresistive effect of improved type sensors is about 1.6-1.8 times greater than that of conventional type sensors. The ratio of the stripe width of the sensors to the recording bit length was found to be an important factor in enlarging the distance from a medium to the sensors.

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Magnetoresistive (MR) effect and anisotropy field (H_k) of NiFe thin film annealed in a direct and rotational magnetic field were studied. In the large size MR element, H_k decreased with temperature up to 300°C due to stress relaxation. When the annealing temperature exceeds 350°C, both Δρ/ρ vs. H curves measured along magnetic hard and easy axis showed large dispersive hysteresis. This resulted in a decrease in Δρ/ρ. In the fine stripe MR element, on the contrary, magnetoresistive and magnetic properties of NiFe film hardly changed at temperature up to 500°C because of shape magnetic anisotropy.
An MR head with magnetic yoke constituted of amorphous CoNbZr was fabricated. The MR head was annealed in a direct and rotational magnetic field in order to obtain high permeability of the yoke. MR characteristics of NiFe film located in the head had a desirable response.

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Polycrystalline Fe₃O₄- and Co-ferrite films were plated on glass- and PET-substrates by a modified method of the electroless ferrite-plating technique, “thin liquid-film (TLF) method.” Aqueous solutions (reaction solution, oxidizing solution) were flowed through the reaction cell (22 × 7 mm², space ∼ 10 μm) in which the substrate had been placed. The reaction was influenced by the flow rates of the reaction solution (v_r) and oxidizing solution (v_o), flow time (t_f) of the oxidizing solution, interval of the flow (t_i) of the oxidizing solution, reaction temperature (T), concentration of the dissolved oxygen in the oxidizing solution (partial pressure of the oxygen in the air/N₂ gas passed through the oxidizing solution, pO₂), and reaction pH. Under the condition where v_r, v_o=15ml/min, t_f=1 s, and t_i=20 s, effects of T, pO₂, and pH on the ferrite plating reaction were studied.

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Fe-Si (0∼16 wt% Si) and Fe-Si-Al (3∼14 wt% Si, 0∼8 wt% Al, bal Fe) alloy films have been prepared by DC sputtering technique. In Fe-Si films, the equilibrium phase expected from the phase diagram could be obtained under the sputtering condition (P_Ar=40 mTorr, V_DC=3.5 kV), while under a different sputtering condition (P_Ar=40 mTorr, V_DC=2.0 kV ), disordered α-phase as a non-equilibrium phase could be realized up to about 16 wt% Si. Concentration dependence of the magnetostriction, λ, for Fe-Si films sputtered under V_DC=3.5 kV was found to be nearly the same as that of bulk crystals. However, for Fe-Si films consisting of the α-phase, the sign of λ remains positive up to about 16 wt% Si. Concentration dependence of zero magnetostriction, λ=0, determined for Fe-Si-Al films is found to be different from that of bulk crystals and also different from that of the evaporated films reported by Kadono et al.. Comparing the concentration dependence of λ with that of magnetocrystalline anisotropy constant, K₁, determined by the present authors, it is proposed that the films with soft magnetic properties such as Sendust alloy be realized in the Fe-rich concentration portion.

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The magneto-optical properties and related magnetic properties were studied for a series of polycrystalline Fe-Ni Invar films prepared by a vacuum evaporation method. The Kerr rotation angle (θ_K) was measured through a glass substrate by the polar Kerr magneto-optic effect using a He-Ne laser (6328 Å). The Kerr rotation angle of Fe₇₁Ni₂₉ increases from 0.032° to 0.165° with decreasing film thickness from 360 Å to 200 Å. However, there is little decrease of θ_K at the top surface boundary of the film. Therefore, the increase of θ_K is believed to be caused by the increase of magnetic moment at the bottom boundary. It is concluded that the interaction between film and substrate is a very important factor in the thickness dependence of the magnetic moment of Invar alloy film (∂M_S/∂D < 0).

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Iron-cobalt alloy thin films (0-54 at.% Co-Fe) were deposited using an ion beam sputtering apparatus and their magnetic properties were investigated in detail.
All of the films have large saturation magnetic flux density above 20 kG. The films deposited at substrate temperature T_s of about 75°C have a large perpendicular magnettc anisotropy field H_k⊥ (>110 Oe) and high coercive force H_c (>50 Oe), while the increase of T_s shows a significant decrease in both H_k⊥ and H_c. The perpendicular magnetic anisotropy of the film deposited at T_s above 250°C disappears completely, and films with Co content of 50-54at.% have the lowest H_c, as low as 5 Oe. The decrease of T_s from 75°C to 250°C also causes a change in the internal stress of the films from compressive to tensile stress along with a growth of crystallites. Annealing the films in a vacuum has nearly the same effect on changes of their magnetic properties and internal stress as the increase of T_s. These changes in magnetic properties with T_s or annealing temperature are considered mainly caused by the change of stress induced magnetic anisotropy energy, since the Fe-Co alloy film has a large positive magnetostriction constant.

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RF reactive sputtering discharge condition was studied by the measurement of temperatures. A thermocouple was set between a target and a substrate. Temperature rapidly changed at critical RF power (Pf₁, and Pf₂) in an Ar-O₂ mixed atmosphere, though such a charge was not observed in an Ar atmosphere. Deposition rate, structure and magnetic properties for the sputter-deposited films also abruptly changed at the critical point of Pf₁ and Pf₂. The Pf₁ and Pf₂ increased with an increase of oxygen partial pressure. The critical RF power, however, decreased with an increase of total pressure, increasing the temperature values. These experimental results were qualitatively explained by an oxidation of the target surface

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In an attempt to fabricate transparent ferromagnetic materials coexisting with ferroelectricity above room temperature, we have examined reactive rf-sputtered films of solid solution compounds with (BiFeO₃)_1-x(PbTiO₃)_x, x=0 to 1. The targets were mixed powders of Bi₂O₃, α-Fe₂O₃, PbTiO₃ and PbO, in which the first two components were used to synthesize BiFeO₃ by 1 : 1 mixing in mol. % and the last component was added by 5 mol. % with respect to PbTiO₃ to compensate the evaporation loss of lead during sputtering. As-grown samples deposited at about 400°C are amorphous but have noticeably large saturation magnetization 4πM_s=210 G and saturation dielectric polarization of P_s=0. 092 μC/cm² at room temperature. The samples are turned into polycrystalline by post-heat treatment at 700°C for 2 hours in air and 4πM_s is increased to about twice as large as the initial one, while P_s is, in most samples, rather decreased. The samples have a high transmittance in the wavelength of visible through near-infrared. The refractive index n of BiFeO₃ film is 3.0 at λ=700 nm.

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CoNbZr amorphous films have attracted the attention of many researchers because of their high saturation magnetization, high permeability, low coercivity, and nearly zero magnetostriction. For the application of these films, one of the important magnetic properties is the behavior of the permeability over a wide frequency range. We have measured the permeability of a square shaped magnetic film (13 mm × 55 mm) sputtered on a glass substrate from 1 MHz to 400 MHz using a stripline. Over 400 MHz, measurement of the permeability of the magnetic film has been made using a ring shaped sample mounted in a coaxial fixture. The wall motion permeability of CoNbZr amorphous films decreases from 1 KHz and becomes nearly zero at 1 MHz. The rotation permeability is constant to 100 MHz and the ferromagnetic resonance is observed near 1 GHz

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A control magnetization curves (CMC) of Co-base amorphous toroidal cores up to 1 MHz have been evaluated for the first time. A field effect transistor was employed as a switching element and the cores were driven by a square wave.
Results are summarized as follows: i) full-reset force and reset power decrease with the decrease of tape thickness. ii) full-reset force is proportional to f^0.8 and reset power to f^1.4∼f^1.8. iii) at f = 1 MHz, full-reset force as small as 21 A/m has been obtained. Maximum value of specific core gain is obtained for the core with low full-reset force and relatively high rectangularity of CMC, and iv) reset power is proportional to ΔB^1.8∼ΔB^2.0 at f = 1 MHz.

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This paper describes the performance characteristics of a bridge-connected magnetic circuit in ac control. The value of output current is easily controlled by varying the phase difference between the control current and supply voltage.
The operation characteristics of a push-pull circuit using two bridge-connected magnetic circuits are also described in this paper.

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A new type of magnetic frequency multiplier is proposed for improved performance. This device has core type output windings installed collectively by combining the cores into a T. The length of output winding of this type device can be reduced to about 56% of the conventional type. The core advantages of the type magnetic frequency multiplier are as follows :
(1) High efficiency equivalent to a large scale device can be obtained easily.
(2) Regulation of output voltage can be reduced.
In this paper, operation of core type frequency multiplier is analysed by the harmonic balance method the considering the unbalance of the circuit. Mechanism of the two step jumps which occur in the nonlinear zero-phase-sequence circuit is clarified by results of the analysis.

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A cloth inductor using amorphous magnetic fibers and conductive fibers with various diameters has been machine-made.
The frequency characteristics of inductance and quality factor have been measured and suitable magnetic materials for the cloth inductor discussed together with optimization of amorphous fiber and conductive fiber size in order to put the cloth inductor into practical use.
A inductor with Q>30 and L_d>10 μH/mm³ is expected to be realized.

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This paper describes loss reduction techniques for a transformer used in a multi-input converter which is powered by a commercial AC power source as well as by batteries. Although the converter circuit configuration is simple, converter loss is comparatively large when the unit is powered by battery and driven at high frequency. The reason for this comparatively large loss is that large distributed capacitance exists in the battery input winding of the multi-input transformer, and the capacitance is alternately charged and discharged through the switching element according to the on-off state of the switching transistor.
One way of effectively reducing this distributed capacitance is to increase the space of each AC input layer. This can be done by incleasing the insulation distance for each layer. It is also shown that loss in a multi-input converter operating at 1 MHz is reduced by about 4 %.

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The orthogonal-core type DC-AC converter exhibits desirable features which include excellent isolation and good controllability. This paper describes the application of the DC-AC converter to a photovoltaic power system which connects the solar cells to the ac line. The results obtained in the trial system using the solar cells and a solar cell simulator indicate that the photovoltaic power system has the following features: simple construction, high reliability and ease of maintenance. The photovoltaic power system presented here is useful for a residential interconnection system.

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In general, residual flux density produces a detrimental effect on a measurement instrument end. an apparatus. This report studies the following problems :
(1) Analysis of residual flux distribution by the finite element method, taking into account of hysteresis.
(2) Demagnetizing conditions of mild steel and the demagnetizing method. The demagnetizing conditions and method were confirmed experimentally and the following experiments on demagnetizing were made: (a) gradient, (b) frequency, and (c) magnitude.

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This paper presents the application of the stochastic finite element method to a magnetic field analysis. The dimensions or the material constants of a magnetic device are considered as probable ones and treated in the space-stochastic process. When magnetic permeability provides uncertain distribution on the surface or in the body of the magnetic material, the uncertainty can be taken into account. In order to obtain the effect of the deviation, a number of repeated calculations are necessary with the conventional finite element method. The present stochastic finite element method, however, needs no repetition, so that computing time can thus be considerably reduced. The calculated standard deviation makes it possible to evaluate the reliability of magnetic materials or power apparatus.

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This paper describes some considerations of the magnetic materials used for small sized parametric motors and their application to a 4-pole parametric motor:
The following items are clarified :
(1) Magnetic isotropic material and easily saturable magnetic material are desirable for a common magnetic ciruit.
(2) Magnetic material with higher saturation magnetic flux density is desirable for an exciting circuit.

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Highly stable and accurate mechanocardiograph sensors are presented using linear magnetdisplacement sensors with a star-shaped amorphous core multivibrator. 2N zero-magnetostrictive amorphous wire cores are newly assembled into a star shape, in which external disturbance fields such as terrestrial fields are almost completely cancelled and the signal field generated by a small magnet is stably detected. These linear displacement sensors can detect the displacement of a magnet through about 3mm with a drift of less than 0.2 μm.
Mechanocardiographs of a heartbeat, a phonocardiograph, and blood-vessel pulsation are stably and easily detected by fixing a small magnet on the chest wall or the blood-vessel position, combined with a non-contact type displacement sensor.

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The wire explosion technique, which is known to give rise to strong adhesion between sprayed layers and substrates, was applied to the prepartion of magnetostrictive layers for sensors. It has been shown that the Ni and/or Fe-Ni layers sprayed in the form of chevron on stainless steel shafts exhibit soft magnetic properties after annealing and are applicable to the constitution of torque sensors showing very linear torque-output characteristics with almost zero hysteresis in combination with a two-core type multivibrator bridge circuit.

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A new circuit for a noncontact torque sensor using a pair of magnetic heads and a magnetostrictive layer on the shaft is proposed. The circuit is very simple and has a selfcompensatory mechanism of sensitivity against fluctuations in the air gap between pole pieces of the heads and the magnetostrictive layer. This self-compensatory mechanism is analyzed in detail. The experimental results obtained using Metglas 2605 S-2 as a magnetostrictive layer are presented, showing the validity of the analysis and the static characteristics.

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Possible influence of ELF (extremely low frequency) magnetic fields or electric fields on the early embryonic development of frogs was studied. African clawed toads, Xenopus laevis, were used. Embryos were exposed to 10-15 mT alternating magnetic fields at different frequencies (20 Hz, 2.0 kHz, and 20 kHz) either during cleavage to neurula stage or the neurula to tail bud stage. During field exposures, the embryos were bred in a cylindrical chamber filled with 1/5 diluted saline solution so that the eddy currents could be induced in the solution. The estimated current densities induced by the ELF magnetic fields were 0.01-10.5 μA/mm². The results show that the magnetic fields exert no harmful or modifying effects on the embryonic development.
In order to obtain the critical current density which gives rise to teratogenic effects, electrical currents were directly applied to the embryos. When the cleavage-stage embryos were exposed to 20Hz electric fields for 8 hrs, the current density of 100 μA/mm² gave lethal value or 100% malformation. When the embryos were exposed to an alternating current of 100 μA/mm² at 20Hz for 15 min in each stage, the cleavage-brastra-stage embryos were those mostly damaged by the field (91 % malformation).

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The effects of magnetic fields on combustion velocity and combustion temperature of alchol with platinum catalysis were studied. The place of combustion reaction was exposed to d. c. magnetic fields with field intensities from 0.1 T to 1.0 T.
Combustion velocity was defined as the mean velocity over the period from ignition to consumption of the fuel. The combution velocity was influenced by a specific magnetic field. The combustion velocity of methanol was observed to be decreased by -5.3% with the application of a magnetic field of 0.9 T.
Instantaneous combustion temperature was measured continuously, before, during, and after magnetic field exposures. The temperature was measured by an infrared thermometer the sensor probe of which was kept a distance from the combustion place and connected to a PbS transducer through an optical fiber. The results show that the combustion temperature of methanol decreased gradually in accordance with the field exposures at 0.9 T.
Fluctuation in temperature variation increased during field exposure of the same intensity (0.9 T).

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