S= 1/2 Quantum Heisenberg Ladder and S = 1 Haldane Phase

Hiroshi Watanabe, Satoshi Takada

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57 Scopus citations


We investigate an S=(1/2) ladder model with a ferromagnetic interchain coupling (-A) and an antiferromagnetic intrachain coupling based on the bosonization method, which reduces to the 5=1 antiferromagnetic Heisenberg model in the limit k0â¥. We argue with the aid of Wilson's renormalization group method that the ground state is the Haldane state with an excitation gap for Xâ0, that the gap opens at A=0 exponentially and that the critical index of the coherence length is unity (v= 1) on the critical line between the antiferromagnetic and the Haldane phases. Furthermore, it is found that the string order parameter proposed by den Nijs and Rommelse is expressed by a local order parameter in the bosonization method.

Original languageEnglish
Pages (from-to)2845-2860
Number of pages16
JournalJournal of the Physical Society of Japan
Issue number8
StatePublished - 15 Aug 1993

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