Quantum phase transitions in multileg spin ladders with ring exchange

Sylvain Capponi (1, 2) , P. Lecheminant (3) , M. Moliner (4, 5)

1 FFC - Fermions Fortement Corrélés (LPT)
2 LPT - Laboratoire de Physique Théorique
3 LPTM - UMR 8089 - Laboratoire de Physique Théorique et Modélisation
4 IPCMS - Institut de Physique et Chimie des Matériaux de Strasbourg
5 ISIS - Institut de Science et d'ingénierie supramoléculaires

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.

Domaines: Autre [cond-mat.other]

Sylvain Capponi, P. Lecheminant, M. Moliner. Quantum phase transitions in multileg spin ladders with ring exchange. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2013, 88 (7), pp.075132. ⟨10.1103/PhysRevB.88.075132⟩. ⟨hal-00910749⟩