The analysis of magnetic entropy change and long-range ferromagnetic order in Mn1-xAgxCoGe
The analysis of magnetic entropy change and long-range ferromagnetic order in Mn1-xAgxCoGe
复制标题
Mn1-xAgxCoGe中磁熵变和长程铁磁有序度分析
DOI：
10.1007/s10853-018-3053-2
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发表时间：
2019
影响因子：
4.5
通讯作者：
Zhou Tao
中科院分区：
文献类型：
--
作者：
Si Xiaodong;Liu Yongsheng;Ma Xinxiu;Lin Jia;Yang Jie;Zhou Tao
MnCoGe合金是一种具有良好室温磁制冷应用前景的合金，其磁热效应与相变性质密切相关。在这项工作中，我们提出了一个系统的研究重点是相变，磁熵变，和磁相互作用在四个组成。利用Banerjee判据、朗道理论和普适行为来判别二级相变的特征。结果表明，基于朗道理论的磁熵变理论值与实验值吻合较好，表明该方法用于评价磁热性能的可靠性。此外，从重新标度的磁熵变曲线和磁场依赖性的磁熵变确定的拟合参数被用来给相变和磁制冷性能的更好的理解。可靠的临界指数，从三种技术建议在这个系统中的长程磁耦合。此外，通过计算有效指数（β eff和γeff）和交换距离J（r）的密度，描述了Ag替代时临界行为的差异。非常稳定的相变性质和丰富的可用性使该系统适合于热磁发电应用。
MnCoGe alloy is a promising candidate for room-temperature magnetic refrigeration applications, and the magnetocaloric effect in this family has a close relationship with the nature of phase transition. In this work, we presented a systematic study focusing on the phase transition, magnetic entropy change, and magnetic interaction in four compositions. The Banerjee criterion, Landau theory, and universal behavior were performed to distinguish the characteristic of second-order transition. It is found that the theoretical magnetic entropy changes based on Landau theory are in good agreement with the experimental findings, indicating the reliability of this method to evaluate magnetocaloric property. Moreover, the fitting parameters determined from the rescaled magnetic entropy change curves and field dependence of magnetic entropy change are used to give a better understanding of phase transition and magnetic refrigerant performance. Reliable critical exponents from three techniques suggest long-range magnetic couplings in this system. Additionally, the differences in critical behavior with Ag substitution are described by calculation of density of the effective exponents (βeffandγeff) and exchange distanceJ(r). The very stable nature of phase transition and abundant availability make this system suitable for thermomagnetic power generation applications.