Coupling of magnetic order and charge transport in the candidate Dirac semimetal EuCd${}_2$As${}_2$

Abstract

We use resonant elastic x-ray scattering to determine the evolution of magnetic order in EuCd${}_2$As${}_2$ below $T_{\text{N}}=9.5$\,K, as a function of temperature and applied magnetic field. We find an A-type antiferromagneticstructure with in-plane magnetic moments, and observe dramatic magnetoresistive effects associated with field-induced changes in the magnetic structure and domain populations. Our \textit{ab initio} electronic structure calculations indicate that the Dirac dispersion found in the nonmagnetic Dirac semimetal Cd${}_3$As${}_2$ is also present in EuCd${}_2$As${}_2$, but is gapped for $T<T_{\text{N}}$ due to the breaking of $C_3$ symmetry by the magnetic structure.

Supplemental information attached to preprint