场诱导下自旋冰系统[111]方向磁相变过程的蒙特卡洛模拟  

CARLO SIMULATION OF FIELD-INDUCED MAGNETIC PHASE TRANSITION IN SPIN ICE ALONG [111] DIRECTION

作　　者：黄平[1] 汤征[1] 袁慧[1] 刘雍[1] 张悦[1] 熊锐[1] 石兢[1] 

机构地区：[1]武汉大学物理系光声材料与器件教育部重点实验室,武汉430072

出　　处：《低温物理学报》2008年第4期303-307,共5页Low Temperature Physical Letters

基　　金：国家自然科学基金(批准号:10674105)资助的课题~~

摘　　要：自旋冰系统因为具有与固体水(冰Ih)中氢原子构型相同的自旋排列局域规则而具有宏观量子简并的基态,即使十分接近零温也不会达到长程磁有序态.外场的诱导将破坏基态的简并而使系统达到长程磁有序.我们在最近邻铁磁相互作用的简化模型下用蒙特卡洛方法模拟了自旋冰系统在[111]方向外场下的磁相变行为.分别给出了不同温度和不同相互作用强度下的磁化曲线,分析了系统的磁化过程中自旋的取向得有序程度以及相变,探讨了相互作用强度对系统磁相变行为的影响.The spin ice system, exactly mapping the local configurations of protons in water ice, exhibits macroscopic degenerated groundstates, without any evidence of formation of long-range ordering in the lowest temperature. External fields can lift the degeneracy and induce long-range ordered states. We studied the phase transition of the system under the [ 111 ] magnetic field with the effective ferromagnetic exchange interaction model. Magnetization curves in different temperatures and with different effective interaction strength were given, respectively. The spin configurations and ordering processes were given. Moreover, different interaction strength＇ s effect was discussed.

关 键 词：几何失措 相变 蒙特卡洛模拟 

分 类 号：O482.5[理学—固体物理]