We investigate magnetic properties of FeAl stripes and dots formed on the surface of Fe₅₂Al₄₈ induced by nanosecond pulsed laser irradiation. According to the in-plane magneto-optical Kerr effect (MOKE) measurements, the magnetization reversal in FeAl stripes can be explained by the domain-wall (DW) motion model, indicating that the magnetization rotates incoherently. In contrast, the in-plane and polar MOKE measurements reveal that the magnetic easy axis of the FeAl dots exists along the out-of-plane direction and the coercive force H_c shows as large as 1 kOe. These results indicate that the nanosecond pulsed laser irradiation can be expected to serve as a useful tool for obtaining magnetic nanostructures and creating high-H_c materials.

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  In-plane and out-of-plane ferromagnetic resonance (FMR) were used to investigate the intrinsic magnetic damping constant (α) in epitaxial Fe₄N thin films deposited on MgO substrates. The dependence of α on temperature was evaluated from room temperature (RT) to 4 K. The external magnetic field (H) of FMR was applied in two directions, i.e., [100] and [110], of the Fe₄N lattice. Anisotropic α was observed from RT to 4 K. Moreover, the α for H // [100] exceeded the α for H // [110] at 180 K. Numerical calculations of α for bulk Fe₄N revealed the same behavior as that in the experiments. The temperature dependence of anisotropic α was explained by the changes in the electronic band structure depending on the directions of magnetization.

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  We investigated the dependence of the sensitivity and noise of fluxgate sensors on the saturation flux density and magnetostriction of an amorphous ribbon core. The relationship between the sensing properties and the domain structures were also investigated with a Kerr microscope. The noise at the zero field increased with the increase in the magnetostriction properties of the core material. The sensitivity decreased with the increase in magnetostriction. Highly magnetostrictive amorphous ribbons had maze domains that were difficult to move by applying a low magnetic field of a few Oersteds. This caused a decrease in the sensitivity of the sensors, and affected noise such as the noise that caused zero drift.

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  Variable inductors, which are composed of only a magnetic core and primary dc and secondary ac windings, can control the effective inductance of the secondary ac winding linearly and continuously by primary dc current due to the magnetic saturation effect. The variable inductors have simple and robust structures, and are highly reliable. Therefore, they are suitable for application as Var compensators in electric power systems. We previously proposed a three-phase laminated-core variable inductor specialized for electric power systems. It had only one laminated-core in which the three-phase secondary ac windings were installed together, in order to reduce the size and weight in comparison with conventional single-phase variable inductors. We propose here a lap-winding type three-phase laminated-core variable inductor that achieves further reduction in size and weight. Basic characteristics of the proposed variable inductor were calculated using finite element method (FEM) and reluctance network analysis (RNA).

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  We created and reported the performance of a variety of magnetic gears in previous work. Magnetic gears allow the transmission of motive force in a completely non-contact state. Their main advantages include low vibration and noise, maintenance-free operation, and a lack of lubrication. We have recently constructed a prototype of a magnetic planetary gear apparatus and found that the most promising practical application of such a device, particularly for accelerator versions, is in wind-powered electrical power generating equipment. This device boasts dual-input functionality. We envision wind power as the primary input, while the secondary input may come from sources such as hydraulic power or electrical-storage devices to drive the mechanism that controls the rotation rate. We reported the possibility of using secondary input as a differential mechanism in a previous paper published in this journal to compensate for variations in the input rotation rate, thus allowing the rotation rate of the sun gear to be controlled, which constitutes the output of the device. We used our dual-input device in this research to carry out experimental investigations into a parallel-drive scheme in which the outer ring gear on the secondary input is rotated in the same direction that the carrier is rotated. Our experiments revealed three distinct operating regimes for our device: a regime in which the output rotation rate was lower than the input rotation rate, a point at which the output rotation rate fell to zero, and a regime in which the output rotation rate was greater than, but in the direction opposite to, the input rotation rate.

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