Exciton topology and condensation in a model quantum spin Hall insulator

Abstract

We study by a consistent mean-field scheme the role on the single- and two-particle properties of a local electron-electron repulsion in the Bernevig, Hughes and Zhang model of a quantum spin Hall insulator. We find that the interaction fosters the intrusion between the topological and non-topological insulators of a new insulating and magnetoelectric phase that breaks spontaneously inversion and time reversal symmetries, but not their product. The approach to this phase from both topological and non-topological sides is signalled by the softening of two exciton branches, i.e., whose binding energy reaches the gap value, that possess, in most cases, finite and opposite Chern numbers, thus allowing this phase being regarded as a condensate of topological excitons. We also discuss how those excitons, and especially their surface counterparts, may influence the physical observables.

References in corpus (15)

• Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells
• Quantum Spin Hall Effect and Topological Field Effect Transistor in Two-Dimensional Transition Metal Dichalcogenides
• Quantum spin Hall effect in a transition metal oxide Na2IrO3
• Room-Temperature Superfluidity in Graphene Bilayers
• Exciton condensation and charge fractionalization in a topological insulator film
• First order character and observable signatures of topological quantum phase transitions
• Fermi surface in the absence of a Fermi liquid in the Kondo insulator SmB${}_6$
• Excitons in topological Kondo insulators - theory of thermodynamic and transport anomalies in SmB${}_6$
• Interaction Driven Subgap Spin Exciton in the Kondo Insulator SmB6
• Surface dead layer for quasiparticles near a Mott transition
• Anomalous 3D bulk AC conduction within the Kondo gap of SmB${}_6$ single crystals
• Excitons and Optical Absorption on the Surface of a Strong Topological Insulator with a Magnetic Energy Gap
• Observation of Chiral Surface Excitons in a Topological Insulator Bi${}_2$Se${}_3$
• The Effects of Spin-Excitons on the Surface States of SmB6: A Photoemission Study
• Chiral Topological Excitons in a Chern Band Insulator