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arXiv · 0806.4416

Topological Identification of Spin-1/2 Two-Leg Ladder with Four-Spin Ring Exchange

I. Maruyama·T. Hirano·Y. Hatsugai
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Abstract

A spin-1/2 two-leg ladder with four-spin ring exchange is studied by quantized Berry phases, used as local order parameters. Reflecting local objects, non-trivial ($π$) Berry phase is founded on a rung for the rung-singlet phase and on a plaquette for the vector-chiral phase. Since the quantized Berry phase is topological invariant for gapped systems with the time reversal symmetry, topologically identical models can be obtained by the adiabatic modification. The rung-singlet phase is adiabatically connected to a decoupled rung-singlet model and the vector-chiral phase is connected to a decoupled vector-chiral model. Decoupled models reveals that the local objects are a local singlet and a plaquette singlet respectively.

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I. Maruyama, T. Hirano, Y. Hatsugai. 2008-06-27. Topological Identification of Spin-1/2 Two-Leg Ladder with Four-Spin Ring Exchange. https://doi.org/10.1103/physrevb.79.115107

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