参量改变对正方晶格纳米岛极化强度的影响  

Effect of parameter change on the polarization of square lattice nanoisland

作　　者：陈胜 卢俊邑 滕保华 CHEN Sheng;LU Jun-yi;TENG Bao-hua(College of Physics,University of Electronic Science and Technology of China,Chengdu,Sichuan 611731,China)

机构地区：[1]电子科技大学物理学院,四川成都611731

出　　处：《大学物理》2021年第10期5-8,21,共5页College Physics

摘　　要：基于横场Ising模型,利用费米型格林函数的通常退耦合近似(MFA)和高阶退耦合近似,研究了自旋为1/2的正方晶格纳米岛的相变性质.极化强度计算表明:在初始自旋取向随机时,可能产生多解及伪解,从而展现出非常规结果,即可重入现象.而利用高阶退耦合近似不但可以解释更为丰富的相变现象,同时绝大部分情况下高阶退耦合近似方程组仅有唯一解,可以很好地避免伪解的产生.另外Js/J是造成极化曲线出现阶梯形状的主要原因,但高阶退耦合近似加大了各参量之间的联系.Based on the transverse field Ising model,the phase transition properties of square lattice nanoislands with a spin of 1/2 are investigated using the usual decoupling approximation and higher order decoupling approximation of the Fermi green function.The polarization diagram shows that when the initial spin orientation is random,multiple and pseudo solutions may be produced,thus show unconventional results:reentry phenomenon.The use of high-order decoupling approximation can not only explain the richer phase transition phenomenon,but also in most cases,the higher-order decoupling approximate equations have only a unique solution,which can avoid the generation of pseudo solutions.J S/J is the main reason for the stepped shape of the polarization curve,but the high order decoupling approximately increases the relationship between the parameters.

关 键 词：纳米岛 格林函数 横场Ising模型 伪解 

分 类 号：O4-1[理学—物理]