A multi-layered master medium with perpendicular anisotropy is proposed. The multi-layered master medium is composed of a thin CoPt film with perpendicular magnetic anisotropy, a nonmagnetic interlayer with several nanometers in thickness, and a soft magnetic FeCo-based film. Magnetic printing characteristics by using single-layered and multi-layered master media were investigated through experiments. The best magnetic printing characteristics were obtained by using the multi-layered master medium. This is because the multi-layered master medium has larger recording field than the single-layered master media near side wall of convex part due to high perpendicular anisotropy of the CoPt film and image effect by the soft magnetic film.

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  The dynamics of the magnetization reversal process in permalloy films by pure spin current injection has been analyzed. We have performed micromagnetics simulations based on the Landau-Lifshitz equation taking into account both the relaxation term and spin transfer torque term caused by the pure spin current which is injected into permalloy thin films laterally. For spin injection from one side of the film sample, the magnetization reversal occurs in film samples less than 70 nm wide. This size is independent of the magnitude of the injected spin current. We also found that spin injection from two sides can reverse the magnetization in permalloy films that are several times wider.

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  Co₅₀Pt₅₀ and Co₅₀Pd₅₀ (at. %) alloy thin films are deposited on MgO(111) single-crystal substrates using an ultra-high vacuum radio-frequency magnetron sputtering system by varying the substrate temperature from room temperature (RT) to 600 °C. The film growth, the film structure, and the magnetic properties are investigated. CoPt epitaxial films with the close-packed plane parallel to the substrate surface are obtained for the investigated substrate temperatures. Ordered phase formation is recognized for CoPt films prepared below 400 °C. As the substrate temperature increases from RT to 300 °C, the degree of order increases from 0.05 to 0.30. With further increasing the substrate temperature, the degree of order decreases. From the view-points of degree of order and atomic stacking sequence of close-packed plane, the crystal structure is determined to vary A3(B_h)+A1(L1₁)→L1₁→A1 with increasing the substrate temperature. On the contrary, CoPd films epitaxially grow above 200 °C, whereas amorphous films are formed below the temperature. No ordered phases are observed for the CoPd films. The crystal structure is determined to be A1 for the CoPd epitaxial films. The lattice strains of these CoPt and CoPd epitaxial films decrease with increasing the substrate temperature. The CoPt epitaxial films with B_h+L1₁ and L1₁ structures show perpendicular magnetic anisotropies. The magnetic properties are influenced by the crystal structure and the degree of order.

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  Knowing the precise positions of a subject and sensors is important to localize the signal source in biomagnetic measurements, such as magnetoencephalography (MEG). Generally, the position of the subject is measured using magnetic marker coils attached to his/her head. The position of the coils should be monitored simultaneously with the MEG measurements. However, the positioning is usually performed before and/or after MEG measurements in order to avoid a crosstalk from marker signals to brain signals. We have developed a simultaneous observation system of MEG signal and marker coil positions using a higher-frequency current driver circuit and multi integrator flux-locked loop circuits. The localization of marker coil was done every 1 s and its accuracy was about 6 mm. We demonstrated the real-time head localization during MEG measurement, and the source position of brain signal could be compensated even if the subject head has moved during the MEG measurement.

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