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Isotropic spin-1 chains with bond alternation: analytic and numerical studies

1995; IOP Publishing; Volume: 7; Issue: 25 Linguagem: Inglês

10.1088/0953-8984/7/25/014

1361-648X

K. Totsuka, Yoshihiro Nishiyama, Naomichi Hatano, Masuo Suzuki,

Quantum many-body systems

Isotropic spin-1 chains with bond alternation are studied. Analytic (both variational and perturbative) results are presented. A phase transition is found to separate the S=1 Haldane phase and the dimer phase. The critical point is numerically determined using the Binder parameter. The universality class is predicted to be given by the level-1 SU(2) Wess-Zumin-Witten model, and this prediction is supported by the present exact diagonalization study. The dimer phase is found to be connected to the "S=2" Haldane phase in a special limit. The change of the excitation spectra and the string order parameter with bond alternation is discussed.