S＝1铁磁模型中阻挫和各向异性引起的量子相变  

Quantum phase transition caused by the frustration and anisotropic effect in the S＝1 ferromagnetic model

作　　者：李俊英[1] 彭晓亮[1] 潘丽华[1] 刘拥军[1] 

机构地区：[1]扬州大学物理科学与技术学院,江苏扬州225002

出　　处：《扬州大学学报（自然科学版）》2012年第2期29-33,共5页Journal of Yangzhou University：Natural Science Edition

基　　金：江苏省科技支撑计划(工业)项目(BE2009106)

摘　　要：利用密度矩阵重整化群(density matrix renormalization group,DMRG)方法研究近邻作用为铁磁耦合、次近邻为反铁磁耦合的一维S=1的各向异性海森堡自旋模型.计算了该系统的基态能、z轴自旋关联函数和面内自旋关联函数.结果表明:各向异性值Δ和阻挫α的相互作用使得系统基态发生相变;在低阻挫区域,Δ>1时系统为铁磁相,0<Δ<1时基态处于自旋液体相;在阻挫较大的区域,自旋关联函数随距离的增大呈现指数函数形式衰减,且具有周期振荡特征,与自旋S=1/2的结果形成鲜明的对比.By using the density matrix renormalization group （DMRG） method, the author investi- gates the diagram of the one-dimensional frustrated anisotropic ferromagnetic S= 1 Heisenberg spin model, in which the nearest neighboring interactions are anisotropic ferromagnetic and the next nea- rest neighboring exchanges are considerable anti-ferromagnetic. The ground state energy and both the in-plane and out-of-plane spin correlation functions are calculated. Apart from the ferromagnetic phase and the spin-fluid phase in the small frustration region, but in the large frustration region, it is identified that spin correlations decay with a short-range exponential law and an oscillating behav- ior. The result is different from the previous result for S=1/2.

关 键 词：密度矩阵重整化群 阻挫 各向异性 铁磁海森堡模型 自旋关联 

分 类 号：O413.1[理学—理论物理]