Band Structure of Two-dimensional Dirac Semimetal from Cyclotron Resonance

TL;DR

This paper demonstrates how cyclotron resonance experiments can directly determine the band structure of a 2D Dirac semimetal, specifically applied to mercury telluride quantum wells, revealing linear and quadratic dispersion features.

Contribution

It introduces a method to invert cyclotron resonance data to map the band structure of 2D materials, bypassing limitations of ARPES in layered thin films.

Findings

Mapped Dirac-like band structure on electron and hole sides

Identified purely linear dispersion for hole-like carriers

Detected quadratic corrections for electron dispersion

Abstract

Knowing the band structure of materials is one of the prerequisites to understand their properties. Therefore, especially in the last decades, angle-resolved photoemission spectroscopy (ARPES) has become a highly demanded experimental tool to investigate the band structure. However, especially in thin film materials with a layered structure and several capping layers, access to the electronic structure by ARPES is limited. Therefore, several alternative methods to obtain the required information have been suggested. Here, we directly invert the results by cyclotron resonance experiments to obtain the band structure of a two-dimensional (2D) material. This procedure is applied to the mercury telluride quantum well with critical thickness which is characterized by a 2D electron gas with linear dispersion relations. The Dirac-like band structure in this material could be mapped both on the electron and on the hole side of the band diagram. In this material, purely linear dispersion of the hole-like carriers is in contrast to detectable quadratic corrections for the electrons.