Exciton condensation in strongly correlated electron bilayers

Abstract

We studied the possibility of exciton condensation in Mott insulating bilayers. In these strongly correlated systems an exciton is the bound state of a double occupied and empty site. In the strong coupling limit the exciton acts as a hard-core boson. Its physics are captured by the exciton t-J model, containing an effective XXZ model describing the exciton dynamics only. Using numerical simulations and analytical mean field theory we constructed the ground state phase diagram. Three homogeneous phases can be distinguished: the antiferromagnet, the exciton checkerboard crystal and the exciton superfluid. For most model parameters, however, we predict macroscopic phase separation between these phases. The exciton superfluid exists only for large exciton hopping energy. Additionally we studied the collective modes and susceptibilities of the three phases. In the superfluid phase we find the striking feature that the bandwidth of the spin-triplet excitations, potentially detectable by resonant inelastic x-ray scattering (RIXS), is proportional to the superfluid density. The superfluid phase mode is visible in the charge susceptibility, measurable by RIXS or electron energy loss spectroscopy (EELS).

21 pages, 14 figures

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Cited by in corpus (15)

• Excitonic condensation in systems of strongly correlated electrons
• Phase diagram of exciton condensate in doped two-band Hubbard model
• Ground state phase diagram of the half-filled bilayer Hubbard model
• Excitons and Dark Fermions as Origins of Mott Gap, Pseudogap and Superconductivity in Cuprate Superconductors --- General Idea and Basic Concept Based on Gap Physics
• Superfluidity and Density Order in a Bilayer Extended Hubbard Model
• How bilayer excitons can greatly enhance thermoelectric efficiency
• Configurational Electronic States in Layered Metallic Dichalcogenides
• Landscape of coexisting excitonic states in the insulating single-layer cuprates and nickelates
• Biexciton Condensation in Electron-hole Doped Hubbard Bilayers -- A Sign-Problem-Free Quantum Monte Carlo Study
• Dynamical response and competing orders in two-band Hubbard model
• Exciton solid in bilayer two dimensional electron-hole systems
• Sign-Free Determinant Quantum Monte Carlo Study of Excitonic Density Orders in a Two-Orbital Hubbard-Kanamori Model
• Excitonic phases in a spatially separated electron-hole ladder model
• Metal-insulator transitions in bilayer electron-hole systems in transition metal dicalcogenides
• Excitonic gap formation in neutral bilayer structures