Localization of trivial edge states in InAs/GaSb composite quantum wells

TL;DR

This paper reports the experimental observation of strong localization of trivial edge states in InAs/GaSb heterostructures, highlighting how disorder affects edge conduction and aligns with localization theories in quasi-1D systems.

Contribution

It provides the first experimental evidence of trivial edge state localization in InAs/GaSb quantum wells with controlled disorder.

Findings

Trivial edge modes are strongly localized in disordered InAs/GaSb heterostructures.

Edge conduction exhibits temperature-independent behavior at low temperatures.

Edge conduction scales exponentially with edge length, consistent with localization theories.

Abstract

InAs/GaSb heterostructure is one of the systems where quantum spin Hall effect is predicted to arise. However, as confirmed by recent experimental studies, the most significant highlight of the effect i.e., the conductance quantization due to non-trivial edge states is obscured by spurious conductivity arising from trivial edge states. In this work, we present experimental observation of strong localization of trivial edge modes in an InAs/GaSb heterostructure which was weakly disordered by silicon delta-like dopants within the InAs layer. The edge conduction which is characterized by a temperature-independent behavior at low temperatures and a power law at high temperatures is observed to be exponentially scaled with the length of the edge. Comprehensive analysis on measurements with a range of devices is in agreement with the localization theories in quasi one-dimensional electronic systems.