Backscattering of Dirac fermions in HgTe quantum wells with a finite gap

TL;DR

This paper investigates how backscattering affects Dirac fermions in HgTe quantum wells with a finite gap, revealing a mobility maximum caused by gap fluctuations, and introduces new insights into Dirac fermion transport with random mass.

Contribution

It demonstrates experimentally and theoretically that mobility anomalies in HgTe quantum wells are due to backscattering from random band gap fluctuations, advancing understanding of Dirac fermion transport with finite mass.

Findings

Mobility exhibits a maximum at certain carrier densities.

Backscattering from gap fluctuations causes the mobility anomaly.

Provides new insights into Dirac fermion transport with finite and random mass.

Abstract

The density-dependent mobility of n-type HgTe quantum wells with inverted band ordering has been studied both experimentally and theoretically. While semiconductor heterostructures with a parabolic dispersion exhibit an increase in mobility with carrier density, high quality HgTe quantum wells exhibit a distinct mobility maximum. We show that this mobility anomaly is due to backscattering of Dirac fermions from random fluctuations of the band gap (Dirac mass). Our findings open new avenues for the study of Dirac fermion transport with finite and random mass, which so far has been hard to access.