Exciton condensation due to electron-phonon interaction

Abstract

We show that the coupling to vibrational degrees of freedom can drive a semimetal excitonic-insulator quantum phase transition in an 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 (non-adiabatic and extreme anti-adiabatic) phonon frequency regime.

14 pages, 8 figures

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• Quantum phase transition in a 1D transport model with boson affected hopping: Luttinger liquid versus charge-density-wave behavior
• Exact treatment of exciton-polaron formation by Diagrammatic Monte Carlo
• Slave boson theory of the extended Falicov-Kimball model
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Cited by in corpus (15)

• Giant exciton Fano resonance in quasi-one-dimensional Ta${}_2$NiSe${}_5$
• Stripe and short range order in the charge density wave of 1T-Cu${}_x$TiSe${}_2$
• Short-range phase coherence and origin of the 1T-TiSe2 charge density wave
• Fate of the excitonic insulator in the presence of phonons
• Competition between excitonic charge and spin density waves: Influence of electron-phonon and Hund's rule couplings
• Nonequilibrium dynamics in the pump-probe spectroscopy of excitonic insulators
• Energy-dependent spatial texturing of the charge order in $1T$-Cu${}_x$TiSe${}_2$
• Electric and magnetic multipoles and bond orders in excitonic insulators
• Photoinduced metallization of excitonic insulators
• Optical signatures of exciton-polarons from diagrammatic Monte Carlo
• Temperature effects in excitonic condensation driven by the lattice distortion
• Impact ionization dynamics in small band-gap 2D materials from a coherent phonon mechanism
• Phase diagram of microcavity exciton-polariton condensates
• Optical amplification in a CDW-phase of a quasi-two dimensional material
• Linear response within the projection-based renormalization method: Many-body corrections beyond the random phase approximation