磁性多层膜磁特性的表面效应  

Monter-Carlo simulation of surface magnetism of multilayered films

作　　者：冯倩[1] 黄志高[1,2] 都有为[2] 

机构地区：[1]福建师范大学物理系,福州350007 [2]南京大学固体微结构物理国家重点实验室,南京210093

出　　处：《物理学报》2003年第11期2906-2911,共6页Acta Physica Sinica

基　　金：国家教育部中青年骨干教师项目 (批准号 :DB 0 41);福建省自然科学基金 (批准号 :E0 0 10 0 2 2 );福建省科学技术厅基金 (批准号 :2 0 0 0Z14 6);国家重点基础研究发展规划项目 (批准号 :G19990 64 5 0 8)资助的课题~~

摘　　要：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 .Based on the Monte-Carlo simulation, the effects of both the ratio of surface interaction to bulk one J(s)/J and the multilayered thickness on the critical behavior are studied. It is found that whether the phase transition temperature increases with increasing number of multilayers depends on the value of J(s)/J. When the value of J(s)/J is above a certain critical value, the system becomes ordered in the surface before it gets in order in the bulk. Below this critical value, one can find that a magnetically disordered surface can coexist with a magnetically ordered bulk phase. For a small J(s)/J, the transition temperature increases slowly with the increase of J(s)/J and finally are equal to the transition temperature of the bulk. When J(s)/J is large enough, the transition temperature increases linearly with the increase of J(s)/J. The simulated results are consistent with those derived by the mean field theory with the transfer matrix method, and well explain the experimental facts.

关 键 词：磁性多层膜 转移矩阵法 交换耦合 MONTE-CARLO模拟 磁相变 表面效应 磁记录材料 尺寸效应 

分 类 号：O484.43[理学—固体物理] TQ584[理学—物理]