UGC-DAE Consortium for Scientific Research, Indore, India.
J Phys Condens Matter. 2012 Sep 26;24(38):386004. doi: 10.1088/0953-8984/24/38/386004. Epub 2012 Aug 28.
The first order martensitic transition in the ferromagnetic shape memory alloy Ni(45)Co(5)Mn(38)Sn(12) is also a magnetic transition and has a large field induced effect. While cooling in the presence of a field this first order magnetic martensite transition is kinetically arrested. Depending on the cooling field, a fraction of the arrested ferromagnetic austenite phase persists down to the lowest temperature as a magnetic glassy state, similar to the one observed in various intermetallic alloys and in half doped manganites. A detailed investigation of this first order ferromagnetic austenite (FM-A) to low magnetization martensite (LM-M) state transition as a function of temperature and field has been carried out by magnetization measurements. Extensive cooling and heating in unequal field (CHUF) measurements and a novel field cooled protocol for isothermal MH measurements (FC-MH) are utilized to investigate the glass like arrested states and show a reverse martensite transition. Finally, we determine a field-temperature (HT) phase diagram of Ni(45)Co(5)Mn(38)Sn(12) from various magnetization measurements which brings out the regions where thermodynamic and metastable states coexist in the HT space, clearly depicting this system as a 'magnetic glass'.
铁磁形状记忆合金 Ni(45)Co(5)Mn(38)Sn(12)中的一级马氏体相变也是一个磁相变，具有较大的磁场诱导效应。在磁场存在的情况下冷却时，一级磁马氏体相变会被动力学捕获。取决于冷却磁场，一部分被捕获的铁磁奥氏体相在最低温度下以磁玻璃态存在，类似于在各种金属间化合物合金和半掺杂锰氧化物中观察到的状态。通过磁化测量对温度和磁场的一级铁磁奥氏体 (FM-A) 到低磁化马氏体 (LM-M) 状态转变进行了详细研究。利用非均匀场的广泛冷却和加热 (CHUF) 测量以及用于等温 MH 测量的新型场冷却方案 (FC-MH) 来研究玻璃状被捕获状态并显示反向马氏体转变。最后，我们从各种磁化测量中确定 Ni(45)Co(5)Mn(38)Sn(12)的场-温度 (HT) 相图，该相图显示了在 HT 空间中热力学和亚稳状态共存的区域，清楚地描绘了该系统作为一个“磁玻璃”。
