Quantum Hall Effect from the Topological Surface States of Strained Bulk HgTe

TL;DR

This study demonstrates the quantum Hall effect arising from topological surface states in a strained bulk HgTe layer, confirming its status as a three-dimensional topological insulator with negligible bulk conduction at very low temperatures.

Contribution

First experimental observation of the quantum Hall effect originating from topological surface states in strained bulk HgTe, establishing its topological insulator properties.

Findings

Quantized Hall effect observed at mK temperatures

Negligible contribution from bulk carriers

Surface states exhibit Dirac-like dispersion

Abstract

We report transport studies on a three dimensional, 70 nm thick HgTe layer, which is strained by epitaxial growth on a CdTe substrate. The strain induces a band gap in the otherwise semi-metallic HgTe, which thus becomes a three dimensional topological insulator. Contributions from residual bulk carriers to the transport properties of the gapped HgTe layer are negligible at mK temperatures. As a result, the sample exhibits a quantized Hall effect that results from the 2D single cone Dirac-like topological surface states.