Surface charge conductivity of topological insulator in a magnetic field: effect of hexagonal warping

TL;DR

This paper examines how hexagonal warping influences the charge transport properties of topological insulators under magnetic fields, revealing significant effects on conductivity, magnetoresistance, and the quantum anomalous Hall effect, aligning with experimental observations.

Contribution

It provides a detailed theoretical analysis of the impact of hexagonal warping on topological insulator transport properties using the Kubo formalism.

Findings

Hexagonal warping increases longitudinal conductivity with disorder.

Warpage causes anisotropic in-plane magnetoresistance.

It influences the quantum anomalous Hall effect.

Abstract

We investigate the influence of the hexagonal warping on the transport properties of the topological insulators. We study the charge conductivity within Kubo formalism in the first Born approximation using low energy expansion of the Hamiltonian near the Dirac point. The effects of disorder, magnetic field and chemical potential value are analyzed in details. We found that the presence of the hexagonal warping effects significantly the conductivity of the topological insulator. In particular, it gives rise to the growth of the longitudinal conductivity with the increase of the disorder and anisotropic anomalous in-plane magnetoresistance. The hexagonal warping also affects the quantum anomalous Hall effect and anomalous out-of-plane magnetoresistance. The obtained results are consistent with the experimental data.