Transport through the network of topological channels in HgTe based quantum well

TL;DR

This paper investigates the transport properties of HgTe quantum wells at critical width, revealing a network of topological channels that influence conductance, and highlighting the system's potential for studying topology and localization interplay.

Contribution

It provides experimental evidence of percolating topological channels in HgTe quantum wells near the Dirac point, advancing understanding of topological insulator networks.

Findings

Confirmation of percolating conducting channels

Presence of a network of helical channels

Potential for studying topology and localization

Abstract

Topological insulators represent a new quantum state of matter which is characterized by edge or surface states and an insulating band gap in the bulk. In a two dimensional (2D) system based on the HgTe quantum well (QW) of critical width random deviations of the well width from its average value result in local crossovers from zero gap 2D Dirac fermion system to either the 2D topological insulator or the ordinary insulator, forming a complicated in-plane network of helical channels along the zero-gap lines. We have studied experimentally the transport properties of the critical width HgTe quantum wells near the Dirac point, where the conductance is determined by a percolation along the zero-gap lines. The experimental results confirm the presence of percolating conducting channels of a finite width. Our work establishes the critical width HgTe QW as a promising platform for the study of the interplay between topology and localization.