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Identification of topologically different valence bond states in spin ladders

Masaaki Nakamura
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Abstract

We discuss relation between three different methods to identify topologically distinct short-range valence-bond ground states in spin-$\frac12$ two-leg ladders: the string order parameters, the level-crossing method, and the ground-state expectation value of the twist operator. For this purpose we reexamine a phase transition in the frustrated spin ladder. We propose a proper bosonization of the string order parameters. Then, these three methods are shown to be equivalent reflecting the $Z_2\times Z_2$ symmetry breaking of the order and the disorder fields of the two-dimensional Ising model.

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Masaaki Nakamura. 2002-10-25. Identification of topologically different valence bond states in spin ladders. https://doi.org/10.1016/s0921-4526(02)02180-4

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