Split Dirac cones in HgTe/CdTe quantum wells due to symmetry-enforced level anticrossing at interfaces

TL;DR

This paper investigates how interface inversion asymmetry causes an anticrossing gap in Dirac states within HgTe/CdTe quantum wells, providing a detailed theoretical and computational analysis of the energy spectrum and potential experimental signatures.

Contribution

It introduces a combined symmetry, atomistic, and k·p theoretical approach to quantitatively describe the Dirac state structure and interface effects in HgTe/CdTe quantum wells.

Findings

Identification of an anticrossing gap caused by interface asymmetry.

Quantitative extraction of the interface mixing coefficient.

Predictions for experimental detection via magnetotransport and optical methods.

Abstract

We describe the fine structure of Dirac states in HgTe/CdHgTe quantum wells of critical and close-to-critical thickness and demonstrate the formation of an anticrossing gap between the tips of the Dirac cones driven by interface inversion asymmetry. By combining symmetry analysis, atomistic calculations, and k-p theory with interface terms, we obtain a quantitative description of the energy spectrum and extract the interface mixing coefficient. The zero-magnetic-field splitting of Dirac cones can be experimentally revealed in studying magnetotransport phenomena, cyclotron resonance, Raman scattering, or THz radiation absorption.