Observation of inverse magnetocaloric effect in magnetic-field-induced austenite phase of Heusler alloys Ni50?xCoxMn31.5Ga18.5 (x=9?and?9.7)
Observation of inverse magnetocaloric effect in magnetic-field-induced austenite phase of Heusler alloys Ni50?xCoxMn31.5Ga18.5 (x=9?and?9.7)
复制标题
Heusler合金Ni50?xCoxMn31.5Ga18.5 (x=9?and?9.7)磁场诱导奥氏体相逆磁热效应观察
DOI：
10.1103/physrevmaterials.5.034416
复制
发表时间：
2021
影响因子：
3.4
通讯作者：
Kanomata T.
中科院分区：
文献类型：
--
作者：
Kihara T.;Roy T.;Xu X.;Miyake A.;Tsujikawa M.;Mitamura H.;Tokunaga M.;Adachi Y.;Eto T.;Kanomata T.
为了研究Heusler合金的磁热性能，在脉冲和稳态强磁场下分别测量了其磁热效应、磁化强度、比热和磁致伸缩。从直接MCE测量高达56 T，一个陡峭的温度下降观察磁场诱导马氏体相变（MFIMT），指定为逆MCE。值得注意的是，这种逆MCE不仅在MFIMT中是明显的，而且在磁场诱导的奥氏体相中也是明显的。在稳定的高磁场下的比热测量结果表明，磁场的电子熵的变化在这些材料的非常规磁热性质中起着主导作用。基于第一性原理的计算结果表明，磁场诱导的奥氏体相比的更不稳定，并且对轻微的四方形变敏感。我们的结论是，在磁场诱导的奥氏体相的逆MCE实现显着的电子熵的变化，通过由外部施加的磁场引起的tetraquintile畸变。
The magnetocaloric effect (MCE), magnetization, specific heat, and magnetostriction measurements were performed in both pulsed and steady high magnetic fields to investigate the magnetocaloric properties of Heusler alloys. From direct MCE measurements forup to 56 T, a steep temperature drop was observed for magnetic-field-induced martensitic transformation (MFIMT), designated as inverse MCE. Remarkably, this inverse MCE is apparent not only with MFIMT, but also in the magnetic-field-induced austenite phase. Specific heat measurements under steady high magnetic fields revealed that the magnetic field variation of the electronic entropy plays a dominant role in the unconventional magnetocaloric properties of these materials. First-principles based calculations performed forandrevealed that the magnetic-field-induced austenite phase ofis more unstable than that ofand that it is sensitive to slight tetragonal distortion. We conclude that the inverse MCE in the magnetic-field-induced austenite phase is realized by marked change in the electronic entropy through tetragonal distortion induced by the externally applied magnetic field.