Abstract

The magnetocaloric effect in a two-dimensional Ising model is considered for different ratios between parameters of inter-site repulsion of nonmagnetic impurities and exchange coupling. Classical Monte Carlo simulations on a square lattice show that in case of weak coupling and at sufficiently high concentrations of nonmagnetic impurities the long-range ferromagnetic ordering breaks down to give isolated spin clusters in the ground state of the system. This leads to appearance of a paramagnetic response in the system at the zero temperature and nonzero entropy of the ground state. The feasibility to detect frustration of ground state using data on the magnetic entropy variation is discussed.

中文翻译：

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二维稀伊辛模型中的磁热效应：基态受挫感的出现

摘要

对于非磁性杂质的位间排斥参数和交换耦合之间的不同比率，考虑了二维Ising模型中的磁热效应。在正方形晶格上的经典蒙特卡洛模拟显示，在弱耦合和非磁性杂质浓度足够高的情况下，远距离铁磁有序分解会在系统的基态下产生孤立的自旋簇。这导致在零温度和基态的非零熵下系统中出现顺磁响应。讨论了使用有关磁熵变的数据来检测基态挫折的可行性。