Striped phase in a quantum XY-model with ring exchange
arXiv:cond-mat/0205270 · doi:10.1103/PhysRevLett.89.247201
Abstract
We present quantum Monte Carlo results for a square-lattice S=1/2 XY-model with a standard nearest-neighbor coupling J and a four-spin ring exchange term K. Increasing K/J, we find that the ground state spin-stiffness vanishes at a critical point at which a spin gap opens and a striped bond-plaquette order emerges. At still higher K/J, this phase becomes unstable and the system develops a staggered magnetization. We discuss the quantum phase transitions between these phases.
4 pages, 4 figures. v2: only minor changes