Identifying topological excitonic insulators via bulk-edge correspondence

Abstract

Excitonic insulator remains elusive and there has been a lack of reliable identification methods. In this work, we demonstrate the promise of topological excitonic insulators for identification due to their unique bulk-edge correspondence, as illustrated by the LiFe$X$ ($X$ = S, Se, and Te) family. First-principles Bethe-Salpeter equation calculations reveal excitonic instabilities in these spin-orbit coupling quantum anomalous Hall insulators. Effective Hamiltonian analyses indicate that spontaneous exciton condensation does not disrupt the gapless edge state but reconstructs the bulk-gap to be almost independent of the spin-orbit coupling strength. This change in the bulk-edge correspondence can be experimentally inspected by angle-resolved photoelectron spectroscopy or electron compressibility measurements, providing observational evidence for the identification of topological excitonic insulators. Moreover, exciton condensation raises the critical temperature of the topological nontrivial phase above room temperature.

Accepted by PRB

References in corpus (30)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Many-body perturbation theory calculations using the yambo code
• Evidence for an excitonic insulator phase in 1T-TiSe${}_2$
• Colloquium: Quantum anomalous Hall effect
• Signatures of exciton condensation in a transition metal dichalcogenide
• Topological Phase Transition and Texture Inversion in a Tunable Topological Insulator
• Tunable symmetry breaking and helical edge transport in a graphene quantum spin Hall state
• Gate-Tuned Spontaneous Exciton Insulator in Double-Quantum Wells
• Evidence for equilibrium excitons and exciton condensation in monolayer WTe2
• Theory of Two-Dimensional Spatially Indirect Equilibrium Exciton Condensates
• Nature of symmetry breaking at the excitonic insulator transition: Ta${}_2$NiSe${}_5$
• High-Temperature Quantum Anomalous Hall Insulators in Lithium-Decorated Iron-Based Superconductor Materials
• Crossover between Strongly-coupled and Weakly-coupled Exciton Superfluids
• MagneticTB: A package for tight-binding model of magnetic and non-magnetic materials
• Carbon nanotubes as excitonic insulators
• Spin-Triplet Excitonic Insulator: The Case of Graphone
• Local probe of bulk and edge states in a fractional Chern insulator
• Theory of the Dirac Half Metal and Quantum Anomalous Hall Effect in Mn Intercalated Epitaxial Graphene
• Half Excitonic Insulator: A Single-Spin Bose-Einstein Condensate
• Realizing intrinsic excitonic insulator by decoupling exciton binding energy from the minimum band gap
• Evidence of ideal excitonic insulator in bulk MoS2 under pressure
• Time-Reversal Symmetry-Breaking Nematic Insulators near Quantum Spin Hall Phase Transitions
• Robust high-temperature topological excitonic insulator of transition-metal carbides (MXenes)
• A New Era of Excitonic Insulators
• Transition from band insulator to excitonic insulator via alloying Se into Monolayer TiS${}_3$: A Computational Study
• Charge-Neutral Electronic Excitations in Quantum Insulators
• One-Dimensional Magnetic Excitonic Insulators
• Electronic and Optical Properties of Ta${}_2$NiSe${}_5$ Monolayer: A First-principles Study
• Spin Hall conductivity in Bi${}_{1-x}$Sb${}_x$ as an experimental test of bulk-boundary correspondence
• First-principles design of excitonic insulators: A review

Cited by in corpus (1)

• Spin-polarized triplet excitonic insulators in Ta3X8 (X=I, Br) monolayers