Exciton condensation due to electron-phonon interaction

Article

关键词: HOLSTEIN MODEL;    PHASE;    INSTABILITY;    TRANSITION;    SEMIMETAL;    INSULATOR;   

DOI  :  10.1103/PhysRevB.88.205123

来源: SCIE

【 摘 要 】

We show that coupling to vibrational degrees of freedom can drive a semimetal excitonic-insulator quantum phase transition in a one-dimensional two-band f-c-electron system at zero temperature. The insulating state typifies an excitonic condensate accompanied by a finite lattice distortion. Using the projector-based renormalization method we analyze the ground-state and spectral properties of the interacting electron-phonon model at half filling. In particular we calculate the momentum dependence of the excitonic order-parameter function and determine the finite critical interaction strength for the metal-insulator transition to appear. The electron spectral function reveals the strong hybridization of f- and c-electron states and the opening of a single-particle excitation gap. The phonon spectral function indicates that the phonon mode involved in the transition softens (hardens) in the adiabatic (nonadiabatic and extreme antiadiabatic) phonon frequency regime.

【 授权许可】

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