Temperature effects in excitonic condensation driven by the lattice distortion

Abstract

The stability of the excitonic condensation at low temperature driven by a coupling of electrons to vibrational degrees of freedom in semimetal two-dimensional electronic system is discussed. In the framework of the unrestricted Hartree-Fock approximation, we derive a set of equations to determine both the excitonic condensate order parameter and lattice displacement self-consistently. By lowering temperature we find out a semimetal-insulator transition in the system if the coupling is large enough. The insulating state typifies an excitonic condensation accompanied by a finite lattice distortion. Increasing temperature, both excitonic condensate order parameter and the lattice distortion decrease and then disappear in the same manner. Microscopic analysis in momentum space strongly specifies that the excitonic condensate driven by the lattice distortion favours the BCS type.

7 pages, 6 figures

References in corpus (10)

• Evidence for an excitonic insulator phase in 1T-TiSe${}_2$
• Room-Temperature Superfluidity in Graphene Bilayers
• Orthorhombic-to-Monoclinic Phase Transition of Ta2NiSe5 Induced by the Bose-Einstein Condensation of Excitons
• Excitonic condensation of massless fermions in graphene bilayers
• Bose-Einstein Condensation of Excitons in Cu${}_2$O: Progress Over Thirty Years
• Bound state formation and nature of the excitonic insulator phase in the extended Falicov-Kimball model
• Chiral charge order in 1$T$-TiSe${}_2$: importance of lattice degrees of freedom
• Weak-coupling Treatment of Electronic (Anti-)Ferroelectricity in the Extended Falicov-Kimball Model
• Hartree-Fock study of electronic ferroelectricity in the Falicov-Kimball model with $f$-$f$ hopping
• Exciton condensation due to electron-phonon interaction

Cited by in corpus (1)

• Phase diagram of microcavity exciton-polariton condensates