Peierls transition in the quantum spin-Peierls model

Journal article

We use the density matrix renormalization group method to investigate the role of longitudinal quantized phonons on the Peierls transition in the spin-Peierls model. For both the XY and Heisenberg spin-Peierls model we show that the staggered phonon order parameter scales as $\sqrt{\lambda}$ (and the dimerized bond order scales as $\lambda$) as $\lambda \to 0$ (where $\lambda$ is the electron-phonon interaction). This result is true for both linear and cyclic chains. Thus, we conclude that the Peierls transition occurs at $\lambda=0$ in these models. Moreover, for the XY spin-Peierls model we show that the quantum predictions for the bond order follow the classical prediction as a function of inverse chain size for small $\lambda$. We therefore conclude that the zero $\lambda$ phase transition is of the mean-field type.

Authors: Barford, W; Bursill, R

• Publication status: Published
• Journal: Physical Review Letters
• Volume: 95
• Issue: 13
• Publication date: 2005-06-06
• DOI: 10.1103/PhysRevLett.95.137207
• EISSN: 1079-7114
• ISSN: 0031-9007
• Keywords: cond-mat.str-el