Phase diagram study of a dimerized spin-S zig-zag ladder

被引:7
作者
Matera, J. M. [1 ]
Lamas, C. A. [1 ]
机构
[1] Univ Nacl La Plata, IFLP CONICET, Dept Fis, Fac Ciencias Exactas, RA-1900 La Plata, Argentina
关键词
magnetism; spin ladder; Heisenberg model; exact ground state; MATRIX RENORMALIZATION-GROUP; MAGNETIZATION PLATEAUS; SYSTEMS; GAP;
D O I
10.1088/0953-8984/26/32/326004
中图分类号
O469 [凝聚态物理学];
学科分类号
070205 ;
摘要
The phase diagram of a frustrated spin-S zig-zag ladder is studied through different numerical and analytical methods. We show that for arbitrary S, there is a family of Hamiltonians for which a fully-dimerized state is an exact ground state, being the Majumdar-Ghosh point for a particular member of the family. We show that the system presents a transition between a dimerized phase to a Neel-like phase for S = 1/2, and spiral phases can appear for large S. The phase diagram is characterized by means of a generalization of the usual mean field approximation. The novelty in the present implementation is to consider the strongest coupled sites as the unit cell. The gap and the excitation spectrum is analyzed through the random phase approximation. Also, a perturbative treatment to obtain the critical points is discussed. Comparisons of the results with numerical methods like the Density Matrix Renormalization Group are also presented.
引用
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页数:15
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