Ni_2MnGaの低温変態と磁歪(磁性体物理・超伝導)

概要

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The thermal transformation and magnetic properties of Ni_<49.0>Mn_<27.2>Ga_<23.8> single crystals were investigated. A martensitic transformation was observed at 172 K during cooling. At this temperature, the strain in the [100] direction under an applied field of 10.1 kOe in a direction parallel to the [100] plane was approximately -8000 ppm. The entropy change in this transformation was estimated as 5.6 J/kg・K by calorimetric measurement. On the other hand, an intermediate phase transformation was observed at 230±2 K. The entropy change was 0.3 J/kg・K. At this temperature, the thermal expansion coefficient was increased, the magnetization in the low - field region was decreased, and the magnetostriction in the [100] direction was increased. The magnetostriction at 232 K was 2.3 times larger in the parallel field and 7.3 times larger at 228 K in the vertical field than the values at room temperature.
社団法人日本磁気学会の論文
2005-03-01