Two-dimensional Dirac fermions in a topological insulator: transport in the quantum limit

TL;DR

This study uses pulsed magnetic fields up to 55T to explore the quantum transport properties of Bi_2Se_3, revealing Landau level quantization of both bulk and surface states and fractional oscillations.

Contribution

It demonstrates the observation of Landau levels in both bulk and surface states of a topological insulator at high magnetic fields, including fractional quantum oscillations.

Findings

Bulk Landau level reached at 4T

Surface state Landau level observed at 35T

Fractional quantum oscillations detected

Abstract

Pulsed magnetic fields of up to 55T are used to investigate the transport properties of the topological insulator Bi_2Se_3 in the extreme quantum limit. For samples with a bulk carrier density of n = 2.9\times10^16cm^-3, the lowest Landau level of the bulk 3D Fermi surface is reached by a field of 4T. For fields well beyond this limit, Shubnikov-de Haas oscillations arising from quantization of the 2D surface state are observed, with the \nu =1 Landau level attained by a field of 35T. These measurements reveal the presence of additional oscillations which occur at fields corresponding to simple rational fractions of the integer Landau indices.