Transport in disordered two-dimensional topological insulator

TL;DR

This study investigates the transport properties of a two-dimensional topological insulator based on HgTe quantum wells, demonstrating long-distance edge state propagation and magnetic field-induced phase transition.

Contribution

It provides experimental evidence of long-range edge state transport and magnetic field effects in HgTe-based topological insulators, highlighting the transition to a bulk metal.

Findings

Edge states propagate over 1 mm distance.

Nonlocal resistance is suppressed by in-plane magnetic field.

Transition from topological insulator to bulk metal observed.

Abstract

We study experimentally the transport properties of "inverted" semiconductor HgTe-based quantum well, which is related to the two-dimensional topological insulator, in diffusive transport regime. We perform nonlocal electrical measurements in the absence of the magnetic field and observe large signal due to the edge states. It demonstrates, that the edge states can propagate over long distance 1 mm, and, therefore, there is no difference between local and non local electrical measurements in topological insulator. In the presence of the in-plane magnetic field we find strong decrease of the local resistance and complete suppression of the nonlocal resistance. We attribute this observation to the transition between topological insulator and bulk metal induced by the in-plane magnetic field.