Two-Dimensional Quantum XY Model with Ring Exchange and External Field
arXiv:cond-mat/0311080 · doi:10.1103/PhysRevB.69.100408
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.
4 pages, 4 figures