Exact-diagonalization study of exciton condensation in electron bilayers

Abstract

We report on small-cluster exact-diagonalization calculations which prove the formation of electron-hole pairs (excitons) as prerequisite for spontaneous interlayer phase coherence in bilayer systems described by the extended Falicov-Kimball model. Evaluating the anomalous Green's function and momentum distribution function of the pairs, and thereby analyzing the dependence of the exciton binding energy, condensation amplitude, and coherence length on the Coulomb interaction strength, we demonstrate a crossover between a BCS-like electron-hole pairing transition and a Bose-Einstein condensation of tightly bound preformed excitons. We furthermore show that a mass imbalance between electrons and holes tends to suppress the condensation of excitons.

6 pages, 5 figures, to appear in Phys. Rev. B

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• Competition between excitonic charge and spin density waves: Influence of electron-phonon and Hund's rule couplings
• A New Era of Excitonic Insulators
• Determinant quantum Monte Carlo study of exciton condensation in the bilayer Hubbard model
• Nonlocal density interactions in auxiliary-field quantum Monte Carlo simulations: application to the square lattice bilayer and honeycomb lattice
• LDA+DMFT approach to ordering phenomena and the structural stability of correlated materials
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• Excitonic Insulator State of the Extended Falicov-Kimball Model in the Cluster Dynamical Impurity Approximation
• Photoinduced metallization of excitonic insulators
• Biexciton Condensation in Electron-hole Doped Hubbard Bilayers -- A Sign-Problem-Free Quantum Monte Carlo Study
• Third-harmonic generation in excitonic insulators
• Sign-Free Determinant Quantum Monte Carlo Study of Excitonic Density Orders in a Two-Orbital Hubbard-Kanamori Model
• Nonequilibrium charge transport through Falicov-Kimball structures connected to metallic leads
• Layer Pseudospin Magnetism in Transition-Metal-Dichalcogenide Double-Moirés
• Gapless regime in the charge density wave phase of the finite dimensional Falicov-Kimball model
• Non-adiabatic and time-resolved photoelectron spectroscopy for molecular systems
• The influence of nonlocal interactions on valence transitions and formation of excitonic bound states in the generalized Falicov-Kimball model
• Excitonic phases in a spatially separated electron-hole ladder model
• DMRG study of exciton condensation in the extended Falicov-Kimball model
• Energetic comparison of exciton gas versus electron-hole plasma in a bilayer two-dimensional electron-hole system
• Unsupervised Machine Learning Phase Classification for Falicov-Kimball Model
• Combined effects of local and nonlocal hybridization on formation and condensation of excitons in the extended Falicov-Kimball model
• Effects of correlated hopping on electronic ferroelectricity in the extended Falicov-Kimball model in two dimensions
• Excitonic gap formation in neutral bilayer structures
• 2D bilayer electron-hole superfluidity with unequal and anisotropic masses
• BCS-BEC crossover of polaritonic condensates in mass-imbalanced semimetal/semiconductor microcavities