一维扩展t-J模型中密度-自旋相互作用诱导的相分离  

Phase separation induced by density-spin interaction in one-dimensional extended t-J model

作　　者：毛斌斌[1] 程晨 陈富州[1] 罗洪刚[1,2] 

机构地区：[1]兰州大学物理科学与技术学院交叉学科研究中心,兰州730000 [2]北京计算科学研究中心,北京100084

出　　处：《物理学报》2015年第18期131-137,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11325417;11174115)资助的课题~~

摘　　要：t-J模型是研究高温超导电性的重要理论模型之一.最近的冷分子实验表明可用极性分子模拟t-J模型.实验模拟的t-J模型除了引进长程的偶极相互作用外,还引进了密度-自旋相互作用.本文使用密度矩阵重整化群方法研究了密度-自旋相互作用对一维t-J模型基态性质的影响.选取了t-J模型基态相图中不同相区的三个点,计算了不同密度-自旋相互作用强度下的粒子数和自旋的实空间分布,以及密度-密度关联函数和自旋-自旋关联函数与相应的结构因子.计算结果表明,密度-自旋相互作用强度较弱时,对系统的性质不会产生定性影响;当其强度足够大时,系统会进入相分离,该相分离与传统t-J模型的相分离有很大区别.t-J model is one of important theoretical models in the study of high temperature superconductivity.Recent cold molecule experiments indicate that t-J model can be simulated by ultracold polar molecules.In the simulated t-J model,besides long-range dipolar interaction,density-spin interaction has also been introduced.In the present paper we study the effect of density-spin interaction in the one-dimensional extended t-J model by using the density matrix renormalization group method.We choose three sets of representative parameters,which correspond to three different phases in the ground state phase diagram of t-J model,to calculate the charge and spin density distribution in real space and the structure factor of density-density and spin-spin correlation functions.The results indicate that the nature of the system will not change if the intensity of the density-spin interaction is small,however if the intensity is large enough,the system enters the phase separation,in which the character is quiet different form that of the phase separation in the traditional t-J model.

关 键 词：T-J模型 密度矩阵重整化群 密度-自旋相互作用 相变 

分 类 号：O511[理学—低温物理] O469[理学—物理]