Band structure of a HgTe-based three-dimensional topological insulator

TL;DR

This paper experimentally determines the band structure of a HgTe-based 3D topological insulator using cyclotron resonance, revealing surface and bulk states and their hybridization, with results aligning with theoretical models.

Contribution

First experimental mapping of the band structure of a HgTe 3D topological insulator using cyclotron resonance and top gating techniques.

Findings

Surface states detected at both film interfaces.

Band structure matches $ extbf{k·p}$ model predictions.

Surface state dispersion is nearly parabolic due to hybridization.

Abstract

From the analysis of the cyclotron resonance, we experimentally obtain the band structure of the three-dimensional topological insulator based on a HgTe thin film. Top gating was used to shift the Fermi level in the film, allowing us to detect separate resonance modes corresponding to the surface states at two opposite film interfaces, the bulk conduction band, and the valence band. The experimental band structure agrees reasonably well with the predictions of the $\mathbf{k\cdot p}$ model. Due to the strong hybridization of the surface and bulk bands, the dispersion of the surface states is close to parabolic in the broad range of the electron energies.