Surface exceptional points in a topological Kondo insulator

Abstract

Correlated materials have appeared as an arena to study non-Hermitian effects as typically exemplified by the emergence of exceptional points. We show here that topological Kondo insulators are an ideal platform for studying these phenomena due to strong correlations and surface states exhibiting a nontrivial spin texture. Using numerical simulations, we demonstrate the emergence of exceptional points in the single-particle Green's function on the surface of the material while the bulk is still insulating. We reveal how quasiparticle states with long lifetimes are created on the surface by non-Hermitian effects while the Dirac cones are smeared, which explains the surface Kondo breakdown at which heavy Dirac cones disappear from the single-particle spectrum and are replaced by light states. We further show how the non-Hermiticty changes the spin texture inherent in the surface states, which might help identify exceptional points experimentally. Besides confirming the existence of non-Hermitian effects on the surface of a topological Kondo insulator, this paper demonstrates how the eigenstates and eigenvalues of the effective non-Hermitian matrix describing the single-particle Green's function help understand the properties of correlated materials.

11 pages

References in corpus (6)

• The numerical renormalization group method for quantum impurity systems
• The physics of exceptional points
• Non-Hermitian Topological Theory of Finite-Lifetime Quasiparticles: Prediction of Bulk Fermi Arc Due to Exceptional Point
• Kondo Breakdown in Topological Kondo Insulators
• Termination-dependent Surface In-gap States in a Mixed-valent Topological Insulator: SmB${}_6$
• R-DMFT study of a non-Hermitian skin effect for correlated systems: analysis based on a pseudo-spectrum

Cited by in corpus (5)

• Low-energy excitations and transport functions of the one-dimensional Kondo insulator
• Spontaneous Formation of Exceptional Points at the Onset of Magnetism
• Hinge non-Hermitian skin effect in the single-particle properties of a strongly correlated f-electron system
• Nodal Spectral Functions Stabilized by Non-Hermitian Topology of Quasiparticles
• Exceptional Luttinger Liquids from sublattice dependent interaction