Exciton condensation in strongly correlated quantum spin Hall insulators

Abstract

Time reversal symmetric topological insulators are generically robust with respect to weak local interaction, unless symmetry breaking transitions take place. Using dynamical mean-field theory we solve an interacting model of quantum spin Hall insulators and show the existence, at intermediate coupling, of a symmetry breaking transition to a non-topological insulator characterised by exciton condensation. This transition is of first order. For a larger interaction strength the insulator evolves into a Mott one. The transition is continuous if magnetic order is prevented, and notably, for any finite Hund's exchange it progresses through a Mott localization before the condensate coherence is lost. We show that the correlated excitonic state corresponds to a magneto-electric insulator which allows for direct experimental probing. Finally, we discuss the fate of the helical edge modes across the excitonic transition.

8 pages, 5 figures

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Cited by in corpus (10)

• Polaron spectroscopy of a bilayer excitonic insulator
• Breakdown of helical edge state topologically protected conductance in time-reversal-breaking excitonic insulators
• Hidden excitonic quantum states with broken time-reversal symmetry
• Mott-Enhanced Exciton Condensation in a Hubbard bilayer
• Topological Gap Opening without Symmetry Breaking from Dynamical Quantum Correlations
• Next-generation EDIpack: A Lanczos-based package for quantum impurity models featuring general broken-symmetry phases, flexible bath topologies and multi-platform interoperability
• Exciton Condensation in Landau Levels of Quantum Spin Hall Insulators
• Band structure picture for topology in strongly correlated systems with the ghost Gutzwiller ansatz
• Topological spin-up triplet excitonic condensation in two-dimensional electron-hole systems
• Excitonic and magnetic phases in doped WTe${}_2$ monolayers: a Hartree-Fock approach