Osamu Kitakami

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Large magnetic-field-induced strains have been observed in Heusler alloys with a body-centred cubic ordered structure and have been explained by the rearrangement of martensite structural variants due to an external magnetic field. These materials have attracted considerable attention as potential magnetic actuator materials. Here we report the(More)
Shape memory and magnetic properties of a Ni 43 Co 7 Mn 39 Sn 11 Heusler polycrystalline alloy were investigated by differential scanning calorimetry, the sample extraction method, and the three-terminal capacitance method. A unique martensitic transformation from the ferromagnetic parent phase to the antiferromagneticlike martensite phase was detected and(More)
The switching fields and thermal stability of CoPt/Ru dot arrays with various dot thickness (5–20 nm) were experimentally investigated as a function of the dot diameter, , (130–300 nm). All dot arrays showed a single domain state, even after removal of an applied field equal to the remanence coercivity. The angular dependence of for the dot arrays indicated(More)
The magnetic properties of dot arrays made of CoPt/Ru perpendicular films (20 nm thickness) were examined as a function of Pt content. The CoPt dot arrays with a dot size of 140 nm showed a single domain state, after removal of the applied field equal to. decreased from 5.2 kOe to 3.0 kOe as the Pt content decreased from 20 at% to 14 at%. The angular(More)
We have studied the switching behavior of a single Co/Pt multilayer dot under the assistance of rf fields. The switching field monotonically decreases with increasing rf frequency up to a critical frequency. It is found that the reduction of the switching field is more significant than the theoretical prediction based on the single macrospin model. In(More)
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