Probing quantum capacitance in a 3D topological insulator

TL;DR

This paper demonstrates how quantum capacitance measurements can directly probe the electronic density of states on the surface of a 3D topological insulator, revealing Landau level spectra and surface-specific properties.

Contribution

It introduces a capacitance-based method to selectively investigate the top surface states of a 3D topological insulator, providing a new tool for surface state analysis.

Findings

Capacitance oscillations primarily probe the top surface.

Capacitance measurements can reconstruct Landau level spectra.

Method offers surface-specific electronic state characterization.

Abstract

We measure the quantum capacitance and probe thus directly the electronic density of states of the high mobility, Dirac type of two-dimensional electron system, which forms on the surface of strained HgTe. Here we show that observed magneto-capacitance oscillations probe, in contrast to magnetotransport, primarily the top surface. Capacitance measurements constitute thus a powerful tool to probe only one topological surface and to reconstruct its Landau level spectrum for different positions of the Fermi energy.