凝聚态物理
磁化
旋转
相变
物理
哈密顿量(控制论)
自旋(空气动力学)
蒙特卡罗方法
磁场
化学
热力学
量子力学
数学
数学优化
统计
作者
Yethreb Essouda,H. T. Diep,M. Ellouze
标识
DOI:10.1016/j.jmmm.2024.172105
摘要
We show by extensive Monte Carlo simulations that we need a multi-spin interaction in addition to pairwise interactions in order to reproduce the temperature dependence of the experimental magnetization observed in the perovskite compound Pr$_{0.67}$Sr$_{0.33}$MnO$_{3}$. The multi-spin interaction is introduced in the Hamiltonian as follows: each spin interacts simultaneously with its four nearest-neighbors. It does not have the reversal invariance as in a pairwise interaction where reversing the directions of two spins leaves the interaction energy invariant. As a consequence, it competes with the pairwise interactions between magnetic ions. The multi-spin interaction allows the sample magnetization $M$ to increase, to decrease or to have a plateau with increasing $T$. In this paper we show that $M$ increases with increasing $T$ before making a vertical fall at the transition temperature $T_C$, in contrast to the usual decrease of $M$ with increasing $T$ in most of magnetic systems. This result is in an excellent agreement with the experimental data observed in Pr$_{0.67}$Sr$_{0.33}$MnO$_{3}$. Furthermore, we show by the energy histogram taken at $T_C$ that the transition is clearly of first order. We also calculate the magnetic entropy change $|\Delta S_m|$ and the Relative Cooling Power (RCP) by using the set of curves of $M$ obtained under an applied magnetic field $H$ varying from 0 to 5 Tesla across the transition temperature region. We obtain a good agreement with experiments on $|\Delta S_m|$ and the values of RCP. This perovskite compound has a good potential in refrigeration application due to its high RCP.
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