Gate tunable quantum Hall effects in defect-suppressed Bi2Se3 films

TL;DR

This paper reports the first demonstration of electrically tunable quantum Hall effects in defect-suppressed Bi2Se3 topological insulator films, revealing a transition from metallic to insulating states at high magnetic fields.

Contribution

It introduces a method to suppress defects in Bi2Se3 films enabling the observation of tunable quantum Hall effects on topological surface states.

Findings

Quantum Hall effects observed on n-side of Bi2Se3

QHE diminishes near charge neutrality point

High magnetic fields induce insulating ground state

Abstract

Despite many years of efforts, attempts to reach the quantum regime of topological surface states (TSS) on an electrically tunable topological insulator (TI) platform have so far failed on binary TI compounds such as Bi2Se3 due to high density of interfacial defects. Here, utilizing an optimal buffer layer on a gatable substrate, we demonstrate the first electrically tunable quantum Hall effects (QHE) on TSS of Bi2Se3. On the n-side, well-defined QHE shows up, but it diminishes near the charge neutrality point (CNP) and completely disappears on the p-side. Furthermore, around the CNP the system transitions from a metallic to a highly resistive state as the magnetic field is increased, whose temperature dependence indicates presence of an insulating ground state at high magnetic fields.