Quantum phase transitions in multileg spin ladders with ring exchange
Abstract
Four-spin exchange interaction has been raising intriguing questions regarding the exotic phase transitions it induces in two-dimensional quantum spin systems. In this context, we investigate the effects of a cyclic four-spin exchange in the quasi-1D limit by considering a general N-leg spin ladder. We show by means of a low-energy approach that, depending on its sign, this ring exchange interaction can engender either a staggered or a uniform dimerization from the conventional phases of spin ladders. The resulting quantum phase transition is found to be described by the SU(2)_N conformal field theory. This result, as well as the fractional value of the central charge at the transition, is further confirmed by a large-scale numerical study performed by means of Exact Diagonalization and Density Matrix Renormalization Group approaches for N \le 4.
Cite
@article{arxiv.1304.6877,
title = {Quantum phase transitions in multileg spin ladders with ring exchange},
author = {S. Capponi and P. Lecheminant and M. Moliner},
journal= {arXiv preprint arXiv:1304.6877},
year = {2013}
}