Quantized lattice dynamic effects on the spin-Peierls transition

Article

关键词: MATRIX RENORMALIZATION-GROUP;    DIMENSIONAL HOLSTEIN MODEL;    PHASE-DIAGRAM;    SYSTEMS;    STATE;    PHONONS;    CHAIN;    POINT;   

DOI  :  10.1103/PhysRevB.82.144408

来源: SCIE

【 摘 要 】

The density-matrix renormalization-group method is used to investigate the spin-Peierls transition for Heisenberg spins coupled to quantized phonons. We use a phonon spectrum that interpolates between a gapped, dispersionless (Einstein) limit to a gapless, dispersive (Debye) limit. A variety of theoretical probes are used to determine the quantum phase transition, including energy gap crossing, a finite-size scaling analysis, bond-order autocorrelation functions, and bipartite quantum entanglement. All these probes indicate that in the antiadiabatic phonon limit a quantum phase transition of the Berezinskii-Kosterlitz-Thouless type is observed at a nonzero spin-phonon coupling, g(c). An extrapolation from the Einstein limit to the Debye limit is accompanied by an increase in g(c) for a fixed optical (q=pi) phonon gap. We therefore conclude that the dimerized ground state is more unstable with respect to Debye phonons with the introduction of phonon-dispersion renormalizing the effective spin-lattice coupling for the Peierls-active mode. We also show that the staggered spin-spin and phonon displacement order parameters are unreliable means of determining the transition.

【 授权许可】

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