Oscillatory angular dependence of the magnetoresistance in a topological insulator Bi_{1-x}Sb_{x}

TL;DR

This study investigates the angular dependence of magnetoresistance and quantum oscillations in a topological insulator, revealing distinct surface and bulk contributions and uncovering new physics in high-field transport phenomena.

Contribution

It identifies two different oscillatory phenomena linked to surface and bulk states, providing a novel method to distinguish 2D surface states from 3D bulk Fermi surfaces in topological insulators.

Findings

Surface state oscillations originate from the (2̅1̅1̅) plane.

High-field oscillations likely from the (111) plane, of unknown origin.

Distinct angular dependence helps differentiate surface and bulk contributions.

Abstract

The angular-dependent magnetoresistance and the Shubnikov-de Haas oscillations are studied in a topological insulator Bi_{0.91}Sb_{0.09}, where the two-dimensional (2D) surface states coexist with a three-dimensional (3D) bulk Fermi surface (FS). Two distinct types of oscillatory phenomena are discovered in the angular-dependence: The one observed at lower fields is shown to originate from the surface state, which resides on the (2\bar{1}\bar{1}) plane, giving a new way to distinguish the 2D surface state from the 3D FS. The other one, which becomes prominent at higher fields, probably comes from the (111) plane and is obviously of unknown origin, pointing to new physics in transport properties of topological insulators.