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利用Monte Carlo方法和转移矩阵法研究了具有不同表面交换耦合Js 和薄膜厚度磁性多层膜的表面和尺寸对磁相变的影响 .模拟结果表明 ,系统的相变温度随薄膜层数的变化取决于Js J(J为体内交换耦合 ) ,当Js J大于某一临界值时 ,由于表面磁有序先于体内磁有序 ,系统的相变温度随薄膜层数的增多而降低 ,反之 ,表面磁无序可与体内磁有序共存 ,系统的相变温度随薄膜层数的增多而升高 ;当Js J较小时 ,随Js 增大 ,系统的居里温度缓慢升高 ,趋近于体内相变温度 ,而当Js J较大时 ,随Js 增大 ,系统的居里温度呈线性升高 .模拟结果与用转移矩阵法推导出的结果相当符合 ,且很好地解释了实验事实 .
The influence of the surface and size of magnetic multilayer films with different surface exchange couplings (Js) and film thickness on the magnetic phase transformation was investigated by Monte Carlo method and transfer matrix method. The simulation results show that the phase transition temperature of the system depends on the film layer number When Js J is larger than a certain critical value, the phase transition temperature of the system decreases with the increase of the number of layers due to the magnetic ordering of the surface before the order of Js J (J is the body exchange coupling). On the contrary, the surface When the Js J is small, with the increase of Js, the Curie temperature of the system slowly increases, approaching the body temperature When the Js J is large, the Curie temperature increases linearly with the increase of Js.The simulation results are in good agreement with the results deduced by the transfer matrix method, and the experimental facts are well explained.