Topological surface states in strained Dirac semimetal thin films

TL;DR

This study computationally investigates the robustness of Fermi arc surface states in strained Dirac semimetal thin films, revealing their persistence under certain symmetry-breaking perturbations and implications for experimental observations.

Contribution

It demonstrates that Fermi arc states in Dirac semimetal thin films are protected by mirror symmetries and can survive symmetry-breaking perturbations, extending understanding of their stability in thin films.

Findings

Fermi arc states persist in very thin films.

Surface states are protected by mirror symmetries.

Symmetry-breaking can significantly affect surface states.

Abstract

We computationally study the Fermi arc states in a Dirac semimetal, both in a semi-infinite slab and in the thin-film limit. We use Cd$_3$A$_2$ as a model system, and include perturbations that break the $C_4$ symmetry and inversion symmetry. The surface states are protected by the mirror symmetries present in the bulk states and thus survive these perturbations. The Fermi arc states persist down to very thin films, thinner than presently measured experimentally, but are affected by breaking the symmetry of the Hamiltonian. Our findings are compatible with experimental observations of transport in Cd$_3$As$_2$, and also suggest that symmetry-breaking terms that preserve the Fermi arc states nevertheless can have a profound effect in the thin film limit.