Magnetic and Superconducting Materials Section, Raja Ramanna Centre for Advanced Technology, Indore, India.
J Phys Condens Matter. 2010 Jan 13;22(1):016008. doi: 10.1088/0953-8984/22/1/016008. Epub 2009 Dec 3.
The martensite to austenite phase transition in the off-stoichiometric Heusler alloy Ni(50)Mn(34)In(16) can be induced both by temperature change and by application of a magnetic field. We have used scanning Hall probe imaging to study the magnetic field induced martensite-austenite phase transition. The study provides clear visual evidence of the coexistence of the martensite and austenite phases across this field induced transition in both increasing and decreasing magnetic fields. Clear evidence of thermomagnetic history effects associated with the martensite-austenite phase transition is also obtained. Quantitative analysis of the magnetic field dependence of the volume fraction of the austenite phase in Ni(50)Mn(34)In(16) shows evidence of a nucleation and growth mechanism across the field induced martensite-austenite phase transition. The local M-H loops constructed from the Hall images indicate the presence of a landscape of the critical magnetic field (for the field induced transition) distributed over the sample volume and thus confirm the disorder influenced nature of this first-order magnetic phase transition.
在化学计量比外的 Heusler 合金 Ni(50)Mn(34)In(16)中，马氏体到奥氏体的相变既可以通过温度变化，也可以通过施加磁场来诱导。我们使用扫描 Hall 探针成像来研究磁场诱导的马氏体-奥氏体相变。该研究提供了明确的视觉证据，证明在这一磁场诱导的相变中，马氏体和奥氏体相在增加和减少磁场中同时存在。还获得了与马氏体-奥氏体相变相关的热磁历史效应的明确证据。对 Ni(50)Mn(34)In(16)中奥氏体相体积分数随磁场变化的定量分析表明，在磁场诱导的马氏体-奥氏体相变中存在形核和生长机制的证据。从 Hall 图像构建的局部 M-H 回路表明，临界磁场（对于磁场诱导的相变）的景观分布在整个样品体积上，从而证实了这种一级磁相变的无序影响性质。
