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Two-Dimensional Quantum XY Model with Ring Exchange and External Field

R. G. Melko·A. W. Sandvik·D. J. Scalapino
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Abstract

We present the zero-temperature phase diagram of a square lattice quantum spin 1/2 XY model with four-site ring exchange in a uniform external magnetic field. Using quantum Monte Carlo techniques, we identify various quantum phase transitions between the XY-order, striped or valence bond solid, staggered Neel antiferromagnet and fully polarized ground states of the model. We find no evidence for a quantum spin liquid phase.

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R. G. Melko, A. W. Sandvik, D. J. Scalapino. 2003-11-04. Two-Dimensional Quantum XY Model with Ring Exchange and External Field. https://doi.org/10.1103/physrevb.69.100408

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