Commensurate-Incommensurate Charge-Density Wave Phase Transition in One-Dimensional Electron-Phonon System. II

Abstract

The Commensurate-Incommensurate (C-IC) phase transition at finite temperature is considered in mean-field approximation taking account of higher harmonics. The phase diagram is given in the (µ, T)-plane, where µ represents a measure of the deviation from 1/3 filledness. It is shown that at proper values of µ successive phase transitions occur (a) from the normal (N) to the IC-phase, (b) from the IC- to be C-phase and (c) from the C- to the IC-phase as T is decreased to zero. The transition (b) is caused by the growth of the amplitude of the order parameter, whereas the transition (c) is due to the increase of the chemical potential.