Inelastic electron backscattering in a generic helical edge channel

TL;DR

This paper investigates how weak interactions and impurity scattering cause temperature-dependent deviations from quantized conductance in a helical edge channel lacking axial spin symmetry, with implications for topological insulator transport.

Contribution

It provides a numerical analysis of inelastic backscattering effects in a generic helical liquid, extending understanding beyond idealized models.

Findings

Conductance deviation scales as T^4 at low temperatures.

Deviation is sensitive to the Fermi level position.

Numerical parameters are determined for a HgTe/CdTe quantum well model.

Abstract

We evaluate the low-temperature conductance of a weakly interacting one-dimensional helical liquid without axial spin symmetry. The lack of that symmetry allows for inelastic backscattering of a single electron, accompanied by forward-scattering of another. This joint effect of weak interactions and potential scattering off impurities results in a temperature-dependent deviation from the quantized conductance, $\delta G \propto T^4$. In addition, $\delta G$ is sensitive to the position of the Fermi level. We determine numerically the parameters entering our generic model for the Bernevig-Hughes-Zhang Hamiltonian of a HgTe/CdTe quantum well in the presence of Rashba spin-orbit coupling.