大学物理 ›› 2021, Vol. 40 ›› Issue (10): 5-.doi: 10.16854 / j.cnki.1000-0712.210233

• 教学研究 • 上一篇    下一篇

参量改变对正方晶格纳米岛极化强度的影响

陈 胜,卢俊邑,滕保华   

  1. 电子科技大学 物理学院,四川 成都 611731
  • 收稿日期:2021-05-10 修回日期:2021-05-26 出版日期:2021-10-15 发布日期:2021-10-15
  • 作者简介:陈胜( 1998—) ,男,湖南长沙人,电子科技大学物理学院 2019 级硕士研究生.

Effect of parameter change on the polarization of square lattice nanoisland

CHEN Sheng,LU Jun-yi,TENG Bao-hua   

  1. College of Physics,University of Electronic Science and Technology of China,Chengdu,Sichuan 611731,China
  • Received:2021-05-10 Revised:2021-05-26 Online:2021-10-15 Published:2021-10-15

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.

关键词: 纳米岛, 格林函数, 横场 Ising 模型, 伪解

Abstract: Based on the transverse field Ising model,the phase transition properties of

square lattice nanois- lands with a spin of 1 /2 are investigated using the usual decoupling

approximation and higher order decoupling ap- proximation of the Fermi green function. The

polarization diagram shows that when the initial spin orientation is ran- dom,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. JS / 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.

Key words: nanoisland, green's function, transverse field Ising model, pseudo-solution