Topological characterization of quantum phase transitions in a spin-1/2 model

We have introduced a novel Majorana representation of S=1/2 spins using the Jordan-Wigner transformation and have shown that a generalized spin model of Kitaev defined on a brick-wall lattice is equivalent to a model of noninteracting Majorana fermions with Z2 gauge fields without redundant degrees...

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Bibliographic Details
Published in:Physical review letters 2007-02, Vol.98 (8), p.087204-087204, Article 087204
Main Authors: Feng, Xiao-Yong, Zhang, Guang-Ming, Xiang, Tao
Format: Article
Language:English
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Summary:We have introduced a novel Majorana representation of S=1/2 spins using the Jordan-Wigner transformation and have shown that a generalized spin model of Kitaev defined on a brick-wall lattice is equivalent to a model of noninteracting Majorana fermions with Z2 gauge fields without redundant degrees of freedom. The quantum phase transitions of the system at zero temperature are found to be of topological type and can be characterized by nonlocal string order parameters (SOP). In appropriate dual representations, these SOP become local order parameters and the basic concept of Landau theory of continuous phase transition can be applied.
ISSN:0031-9007
1079-7114
DOI:10.1103/PhysRevLett.98.087204