We present a theory for thin films of the Dirac semimetal Cd3As2 in the presence of magnetic fields. We show that, above a critical thickness, specific subbands n of thin film Cd3As2 are in a quantum spin Hall insulator regime and study their response to in- and out-of-plane magnetic fields. We find that sufficiently large in-plane Zeeman fields drive the system toward a 2D Dirac semimetal regime, provided the field is directed perpendicular to a high-symmetry mirror plane. For other directions, we find the Dirac points to be weakly gapped. We further investigate how the system responds to finite out-of-plane field components, both starting from the quantum spin Hall regime at small in-plane fields and from the 2D Dirac semimetal regimes at larger in-plane fields, addressing recent experimental observations in [A. C. Lygo et al., Phys. Rev. Lett. 130 046201 (2023)] and [B. Guo et al., Phys. Rev. Lett. 131, 046601(2023)].
@article{arxiv.2401.07839,
title = {Theory for Cd$_3$As$_2$ thin films in the presence of magnetic fields},
author = {M. Smith and V. L. Quito and A. A. Burkov and P. P. Orth and I. Martin},
journal= {arXiv preprint arXiv:2401.07839},
year = {2024}
}