Kondo Tunneling into a Quantum Spin Hall Insulator

TL;DR

This paper investigates how Kondo correlations interact with quantum spin Hall edge states in a junction involving a 2D topological insulator, revealing unique conductance behaviors influenced by edge state coupling.

Contribution

It provides a theoretical analysis of Kondo tunneling in a quantum spin Hall insulator, highlighting the effects of edge state interactions on electron transport.

Findings

Strong edge state coupling suppresses the Kondo peak in conductance.

A zero-bias dip appears in differential conductance when edge states are strongly coupled.

Kondo screening is less effective due to edge state interactions.

Abstract

The physics of a junction composed of a normal metal, quantum dot and 2D topological insulator (in a quantum spin Hall state) is elucidated. It maifests a subtle combination of Kondo correlations and quantum spin Hall edge states moving on the opposite sides of the 2D topological insulator. In a narrow strip geometry these edge states interact and a gap opens in the edge state spectrum. Consequently, Kondo screening is less effective and that affects electron transport through the junction. Specifically, when edge state coupling is strong enough, the tunneling differential conductance develops a dip at zero temperature instead of the standard zero bias Kondo peak.