Many-Body Effects in Topological Kondo Insulators

TL;DR

This paper investigates how interactions influence the phases of a 2D topological Kondo insulator, revealing multiple phases including a unique edge state phase with spontaneously broken time-reversal symmetry.

Contribution

It introduces a model capturing the interplay of Kondo screening and magnetic order, highlighting a novel edge phase with broken TR symmetry not present in non-interacting models.

Findings

Identification of three distinct phases with different magnetic and Kondo properties

Discovery of a phase with a time-reversal invariant bulk but broken TR symmetry at the edge

Discussion on the stability of the edge phase beyond mean field approximation

Abstract

We study the effect of interactions on the properties of a model 2D topological Kondo insulator phase. Loosely motivated by recent proposals where graphene is hybridized with impurity bands from heavy adatoms with partially filled d-shells, we introduce a model Hamiltonian which we believe captures the essential physics of the different competing phases. We show that there are generically three possible phases with different combinations of Kondo screening and magnetic order. Perhaps the most dramatic example of many-body physics in symmetry protected topological phases is the existence of the exotic edge states. We demonstrate that our mean field model contains a region with a time-reversal invariant bulk phase but where TR symmetry is spontaneously broken at the edge. Such a phase would not be possible in a non-interacting model. We also comment on the stability of this phase beyond mean field theory.