Tunable Surface Conductivity in Bi2Se3 Revealed in Diffusive Electron Transport

TL;DR

This paper investigates how weak antilocalization effects can be used to detect and analyze surface transport in topological insulator thin films, revealing tunable surface conductivity and independent surface channels.

Contribution

It demonstrates a method to identify decoupled surface states in Bi2Se3 using magnetotransport measurements and clarifies the role of electron density in surface conduction behavior.

Findings

Weak antilocalization indicates decoupled surface transport.

Lowering electron density reveals independent top and bottom surface channels.

Zeeman energy effects on conductivity are negligible despite interactions.

Abstract

We demonstrate that the weak antilocalization effect can serve as a convenient method for detecting decoupled surface transport in topological insulator thin films. In the regime where a bulk Fermi surface coexists with the surface states, the low field magnetoconductivity is described well by the Hikami-Larkin-Nagaoka equation for single component transport of non-interacting electrons. When the electron density is lowered, the magnetotransport behavior deviates from the single component description and strong evidence is found for independent conducting channels at the bottom and top surfaces. The magnetic-field-dependent part of corrections to conductivity due to the Zeeman energy is shown to be negligible despite non-negligible electron-electron interactions.