Influence of Helical Spin Structure on the Magnetoresistance of an Ideal Topological Insulator

TL;DR

This paper explores how perpendicular magnetic fields influence the spin structure and surface conductivity of ideal topological insulators, revealing a magnetic-field-dependent enhancement factor that varies with disorder type.

Contribution

It introduces a model calculating the magnetic-field dependence of the topological enhancement factor considering different disorder potentials in topological insulators.

Findings

Maximum enhancement factor of 4 at zero magnetic field for short-range disorder

Enhancement factor approaches 1 at high magnetic fields regardless of disorder type

Magnetic field suppresses the topological enhancement of surface conductivity

Abstract

In an ideal topological insulator, the helical spin structure of surface electrons suppresses backscattering and thus can enhance surface conductivity. We investigate the effect of perpendicular magnetic field on the spin structure of electrons at the Fermi energy and calculate a magnetic-field dependent topological enhancement factor for different disorder potentials, ranging from short-range disorder to screened Coulomb potential. Within the Boltzmann approximation, the topological enhancement factor reaches its maximum value of 4 for a short-range disorder at zero magnetic field and approaches a value of 1 at high magnetic fields independent of the nature of the disorder potential.