Helical edge resistance introduced by charge puddles

TL;DR

This paper investigates how charge puddles in a 2D topological insulator affect helical edge conductance, revealing inelastic backscattering effects and resistance dependence on temperature and doping, supported by experimental comparisons.

Contribution

It models electron puddles as quantum dots and analyzes their impact on edge conductance, providing new insights into inelastic backscattering mechanisms.

Findings

Single puddles cause significant inelastic backscattering.

Multiple puddles lead to temperature-dependent resistance.

Results align with recent experimental observations.

Abstract

We study the influence of electron puddles created by doping of a 2D topological insulator on its helical edge conductance. A single puddle is modeled by a quantum dot tunnel-coupled to the helical edge. It may lead to significant inelastic backscattering within the edge because of the long electron dwelling time in the dot. We find the resulting correction to the perfect edge conductance. Generalizing to multiple puddles, we assess the dependence of the helical edge resistance on temperature and doping level, and compare it with recent experimental data.