混合梳子模型中反铁磁阻挫引起的量子相变  

Effect of the diagonal antiferromagnetic frustration on the two-leg ferromagnetic comb model

作　　者：潘丽华[1] 彭晓亮[1] 李俊英[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3期30-34,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：利用严格对角化和密度矩阵重整化群方法研究近邻作用为铁磁耦合、对角的次近邻自旋为反铁磁耦合的两条链的混合梳子S=1/2海森堡模型,计算了该系统的基态能和基态总自旋.结果表明:当阻挫α≤0.25时,系统基态是单纯的铁磁态;随着阻挫的增强,系统基态经历一段总自旋S≠0的倾斜相,再转变到S=0的反铁磁态;与其不同的是,在混合梯子模型中,基态从单纯的铁磁态直接转变成S=0的反铁磁态.By using exact diagonalization method and density matrix renormalization group method, the author studies the ground states of the two-leg spin-1/2 mixed comb model, of which the nea- rest-neighbor interaction is ferromagnetic（FM） and the diagonal next-nearest-neighbor interaction is antiferromagnetic（AF）. The ground state energy and the total spin are analyzed. When α≤0.25, the ground states are simply FM. With the diagonal AF frustration increasing, the ground state transforms from FM state to a canted state region, and then to the S=0 AF state. Differently in the mixed ladder model, the ground state directly transforms from FM state to AF state.

关 键 词：严格对角化 密度矩阵重整化群 反铁磁阻挫效应 海森堡模型 

分 类 号：O413.1[理学—理论物理]