Abstract The magnetocaloric effect in orthorhombic MnCoGe1−xCux (x = 0.0–0.35) alloys are investigated by combining density functional theory (DFT) and Monte-Carlo simulation. The long-range interactions of the magnetic exchange coupling constants evaluated by the DFT calculations are considered for the Monte-Carlo simulation. The magnetic phase transition temperature is estimated by the divergence of the specific heat, and the isothermal entropy change is computed by integrating the isothermal magnetization curves with the Maxwell relation. The magnetic exchange coupling constants of the Mn-Mn pairs is decreased significantly with increasing of the concentration of Cu from 0.0 to 0.35, resulting in the rapid decrease of the Curie temperature from 618 K to 28 K. Not only the Curie temperature of the MnCoGe alloy is controllable by changing the concentration of Cu at Ge site, but also the magnetocaloric properties such as isothermal magnetic entropy change and relative cooling power are strongly dependent on the concentration of Cu.

中文翻译：

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通过第一性原理计算和蒙特卡罗模拟研究 MnCoGe 合金中的磁热效应

摘要 通过结合密度泛函理论 (DFT) 和蒙特卡罗模拟研究了正交 MnCoGe1-xCux (x = 0.0-0.35) 合金的磁热效应。蒙特卡罗模拟考虑了由 DFT 计算评估的磁交换耦合常数的长程相互作用。磁相变温度是通过比热的发散来估计的，等温熵变是通过将等温磁化曲线与麦克斯韦关系积分来计算的。随着Cu浓度从0.0增加到0.35，Mn-Mn对的磁交换耦合常数显着降低，导致居里温度从618 K迅速降低到28 K。