Electron-hole scattering limited transport of Dirac fermions in a topological insulator

TL;DR

This study explores how electron-hole scattering influences transport in the Dirac surface states of a topological insulator, revealing non-monotonic resistance behavior driven by carrier heating and interband interactions.

Contribution

It provides experimental evidence of electron-hole scattering effects on transport in topological insulators, highlighting the role of van Hove singularities in these processes.

Findings

Non-monotonic differential resistance observed with carrier heating.

Electron-hole scattering causes initial resistance increase.

Fermi energy shifts explain subsequent resistance decrease.

Abstract

We experimentally investigate the effect of electron temperature on transport in the two-dimensional Dirac surface states of the three-dimensional topological insulator HgTe. We find that around the minimal conductivity point, where both electrons and holes are present, heating the carriers with a DC current results in a non-monotonic differential resistance of narrow channels. We show that the observed initial increase in resistance can be attributed to electron-hole scattering, while the decrease follows naturally from the change in Fermi energy of the charge carriers. Both effects are governed dominantly by a van Hove singularity in the bulk valence band. The results demonstrate the importance of interband electron-hole scattering in the transport properties of topological insulators.