# Two-dimension Dirac fermions system in CdHgTe quantum wells

## TL;DR

This study investigates two CdHgTe quantum wells, revealing one hosts massless Dirac fermions with high quality, and the other exhibits a topological insulator state with a sizable energy gap, advancing understanding of 2D Dirac systems.

## Contribution

It demonstrates the realization of high-quality 2D Dirac fermions and topological insulator states in CdHgTe quantum wells with specific compositions and thicknesses.

## Key findings

- First quantum well hosts massless Dirac fermions with improved quality.
- Second quantum well shows a topological insulator state with a 10 meV gap.
- Well-defined edge transport observed in the second quantum well.

## Abstract

We report on transport and capacitance spectroscopy study of two kinds of quantum wells, namely Cd$_{0.02}$Hg$_{0.98}$Te and Cd$_{0.06}$Hg$_{0.94}$Te with the thicknesses of 7.4 and 11.5 nm, accordingly. The fraction of Cd was chosen in a way that the both quantum wells are expected to have gapless band structure typical for a Dirac fermions system. We have established that the first quantum well exhibits a massless Dirac fermions system with a quality slightly better then in conventional HgTe quantum wells of critical thickness. Second quantum well exhibits a high-quality two-dimensional topological insulator state with the energy gap of around 10 meV and well-defined edge transport making it as a good candidate for further study and applications of topological insulators.