Quantum oscillations in a topological insulator Bi_{1-x}Sb_{x}

TL;DR

This study investigates the electronic properties of Bi_{1-x}Sb_{x} topological insulators, revealing coexistence of 2D and 3D Fermi surfaces through quantum oscillations, thus providing insights into their surface and bulk states.

Contribution

It demonstrates the use of quantum oscillations to directly probe the complex electronic states in topological insulators, highlighting the coexistence of surface and bulk Fermi surfaces.

Findings

Observation of strong quantum oscillations indicating 2D Fermi surface

Detection of a 3D Fermi surface coexisting with the 2D surface states

Implication of bulk-surface coupling in topological insulators

Abstract

We have studied transport and magnetic properties of Bi_{1-x}Sb_x, which is believed to be a topological insulator - a new state of matter where an insulating bulk supports an intrinsically metallic surface. In nominally insulating Bi_{0.91}Sb_{0.09} crystals, we observed strong quantum oscillations of the magnetization and the resistivity originating from a Fermi surface which has a clear two-dimensional character. In addition, a three-dimensional Fermi surface is found to coexist, which is possibly due to an unusual coupling of the bulk to the surface. This finding demonstrates that quantum oscillations can be a powerful tool to directly probe the novel electronic states in topological insulators.