Competition between weak localization and antilocalization in topological surface states

TL;DR

This paper presents a magnetoconductivity formula for topological insulator surface states, revealing a tunable crossover between weak localization and antilocalization driven by magnetic doping and energy gap effects.

Contribution

It introduces a new theoretical model capturing the competition between weak localization and antilocalization in magnetically doped topological insulators.

Findings

Random magnetic scattering drives the system from symplectic to unitary class.

Energy gap can induce a crossover from weak antilocalization to localization.

The crossover is tunable by Fermi energy and gap size.

Abstract

A magnetoconductivity formula is presented for the surface states of a magnetically doped topological insulator. It reveals a competing effect of weak localization and weak antilocalization in quantum transport when an energy gap is opened at the Dirac point by magnetic doping. It is found that, while random magnetic scattering always drives the system from the symplectic to the unitary class, the gap could induce a crossover from weak antilocalization to weak localization, tunable by the Fermi energy or the gap. This crossover presents a unique feature characterizing the surface states of a topological insulator with the gap opened at the Dirac point in the quantum diffusion regime.