Quantum phase transitions in three-leg spin tubes

Article

关键词: NONLINEAR SIGMA-MODEL;    BOND GROUND-STATES;    HEISENBERG-ANTIFERROMAGNET;    RENORMALIZATION-GROUP;    INTEGER-SPIN;    FIELD-THEORY;    2 DIMENSIONS;    HALDANE-GAP;    CHAIN;    LATTICE;   

DOI  :  10.1103/PhysRevB.82.075108

来源: SCIE

【 摘 要 】

We investigate the properties of a three-leg quantum spin tube using several techniques such as the density-matrix renormalization-group (DMRG) method, strong-coupling approaches and the nonlinear sigma model. For integer S, the model proves to exhibit a particularly rich phase diagram consisting of an ensemble of 2S phase transitions. They can be accurately identified by the behavior of a nonlocal string order parameter associated to the breaking of a hidden symmetry in the Hamiltonian. The nature of these transitions is further elucidated within the different approaches. We carry a detailed DMRG analysis in the specific cases S = 1. The numerical data confirm the existence of two Haldane phases with broken hidden symmetry separated by a trivial singlet state. The study of the gap and of the von Neumann entropy suggest a first-order phase transition but at the close proximity of a tricritical point separating a gapless and a first-order transition line in the phase diagram of the quantum spin tube.

【 授权许可】

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