Topological Antiferromagnetic Spintronics: A case study of EuZnSb₂

Study of the interplay between band topology and magnetism is interesting and important for quantum spintronics applications. Last few years have witnessed a flurry of activities along this direction thanks to the successful prediction and discovery of several promising magnetic topological material candidates. However, in most of the strongly correlated magnetic topological systems discovered to date, especially the f-electron systems, the connection between the Dirac bands and magnetism is not obvious most of the times as the f-electrons lie far away from the Fermi level and do not contribute to the Dirac states. Here, we present a systematic study of a recently synthesized layered antiferromagnetic (AFM) square-net topological semimetal EuZnSb₂ [1] and study its electronic structures and magnetic properties by employing the first-principles and effective Hamiltonian methods. We find that although the Dirac-like linear bands are present irrespective of the magnetic orderings, magnetism does play a subtle role in the topological classification and brings small but non-negligible changes in the gap size across the spectrum. Moreover, the broken symmetry introduced by the ordering of the magnetic moments is manifested in the bulk and surface electronic structures which in turn gives rise to distinct Berry curvature related transport properties. We discuss the experimental implications of our results and generalize our findings to other magnetic topological systems. [1] A. Wang et al., Phys. Rev. Research 2, 033462 (2020); 3, 029002 (2021).