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arXiv · 1304.6877

Quantum phase transitions in multileg spin ladders with ring exchange

S. Capponi·P. Lecheminant·M. Moliner
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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.

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S. Capponi, P. Lecheminant, M. Moliner. 2013-08-20. Quantum phase transitions in multileg spin ladders with ring exchange. https://doi.org/10.1103/physrevb.88.075132

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