Critical behavior and magnetic entropy change at magnetic phase transitions in Ni50Mn35In14Si1 ferromagnetic shape memory alloy
Critical behavior and magnetic entropy change at magnetic phase transitions in Ni50Mn35In14Si1 ferromagnetic shape memory alloy
复制标题
DOI：
10.1209/0295-5075/108/66004
复制
发表时间：
2014-12
期刊：
影响因子：
--
通讯作者：
R. Das;P. Alagarsamy;A. Srinivasan
中科院分区：
文献类型：
--
作者：
R. Das;P. Alagarsamy;A. Srinivasan
测定了Ni50Mn35In14Si1多晶合金在奥氏体居里温度和马氏体居里温度下的二阶铁磁相变(SOPT)附近的临界行为和磁热效应，测定了对应于自发磁化强度、初始磁化率和等温磁化强度随温度变化的临界指数β，γ和δ。利用麦克斯韦关系和临界指数的值估计了两个TC处磁熵变最大值的场依赖关系。这两种方法得到的SOPT值都有显著的一致性。用两种不同的方法，即修正的Arrott图法和Widom标度关系式，通过分析等温磁化数据确定了临界指数。在线性和对数尺度上绘制的标度图证实了所获得的临界指数值的可靠性。多晶Ni50Mn35In14Si1合金在两个转变温度下的临界指数与平均场理论的预测值接近，证实了所研究的合金中存在长程磁有序。
We have investigated critical behaviour and magnetocaloric effect in polycrystalline Ni50Mn35In14Si1 alloy near the second-order ferromagnetic phase transitions (SOPT) at austenite Curie temperature and at martensite Curie temperature by determining the critical exponents, β, γ and δ corresponding to the temperature dependence of spontaneous magnetization, initial susceptibility and isothermal magnetization, respectively. The field dependence of the maximum value of the magnetic entropy change at the two TC's was estimated using the Maxwell relation as well as from the values of the critical exponents. Values of obtained by these two methods at both the SOPT are in remarkable agreement with each other. The critical exponents have been determined by analysing isothermal magnetization data using two different methods, viz., the modified Arrott plot method and the Widom scaling relation. The scaling plots depicted on linear as well as logarithmic scales confirm the reliability of the values of critical exponents obtained. The values of the critical exponents of polycrystalline Ni50Mn35In14Si1 alloy at both the TC's are close to those predicted by mean-field theory confirming the presence of long-range magnetic ordering in the investigated alloy.