Development of temperature measurements in pulsed magnetic fields and its application to magnetic shape-memory alloys

我们发展了脉冲强磁场中样品温度的高速测量。在脉冲磁场中，由于在短脉冲磁场作用下，样品与热浴之间的热交换很小，因此很容易实现绝热磁化过程。因此，我们建立了高达55T的脉冲场中磁热效应的可靠测量。利用该系统，我们测量了磁性形状记忆合金的磁热效应，这被认为是大的逆磁热效应。我们的实验结果首次阐明了这种效应的直接证据。此外，通过对结果的仔细讨论，我们成功地评估了自旋、电荷和晶格对这一效应的每一种贡献，并得出结论，晶格部分对这一效应的贡献最大。

We developed high-speed measurements of sample temperature in pulsed high magnetic fields. In pulsed magnetic fields, we can easily achieve adiabatic magnetization process because of the small heat exchange between the sample and thermal bath in the short duration of pulsed field. Thus, we established reliable measurements of magneto-caloric effects in pulsed fields up to 55 T. With using this system, we measured magneto-caloric effects in magnetic shape memory alloys, which has been regarded to show large inverse magneto-caloric effects. Our experimental results clarified the direct evidence of this effect for the first time. In addition, through careful discussion on the results, we succeeded in evaluating each contribution of spin, charge, and lattice to this effect, and concluded the lattice sector showed the largest contribution to this effect.