Two-dimensional topological insulator edge state backscattering by dephasing

TL;DR

This paper investigates how dephasing and elastic scattering in charge puddles near the edges of two-dimensional topological insulators affect conductance, providing insights into experimental observations and proposing new experimental and computational methods.

Contribution

It introduces a numerical approach to quantify dephasing effects on topological insulator edge states and suggests experiments to verify the role of charge puddles in conductance behavior.

Findings

Dephasing and elastic scattering influence edge conductance in topological insulators.

Large, weakly coupled charge puddles can explain experimental conductance signatures.

A new wave-packet evolution method incorporates dephasing effects.

Abstract

To understand the seemingly absent temperature dependence in the conductance of two-dimensional topological insulator edge states, we perform a numerical study which identifies the quantitative influence of the combined effect of dephasing and elastic scattering in charge puddles close to the edges. We show that this mechanism may be responsible for the experimental signatures in HgTe/CdTe quantum wells if the puddles in the samples are large and weakly coupled to the sample edges. We propose experiments on artificial puddles which allow to verify this hypothesis and to extract the real dephasing time scale using our predictions. In addition, we present a new method to include the effect of dephasing in wave-packet-time-evolution algorithms.