Pressure Effect on Band Inversion in <i>AE</i>Cd₂As₂

Recent studies have predicted that magnetic EuCd₂As₂ can host several different topological states depending on its magnetic order¹, including a single pair of Weyl points². Here we report on the bulk properties and band inversion induced by negative pressure in the nonmagnetic analogs AECd₂As₂ (AE = Ca, Sr, Ba) as studied with density functional theory calculations. Under ambient pressure we find these compounds are narrow band gap semiconductors, in agreement with experimental reports. The application of negative pressure reduces this band gap and causes a band inversion which results in four-fold degenerate Dirac points. The topological nature of these Dirac points is then confirmed by finding the closed Fermi arcs on (10-10) surface. Due to the relatively small negative pressures predicted to reach these Dirac semi-metallic states, we argue that experimental realization can be achievable by the alloying of AECd₂As₂.

¹G. Hua et al., Phys. Rev. B 98, 201116 (2018)., ²L.-L. Wang et al., Phys. Rev. B 99, 245147 (2019).