Topological Antiferromagnetic Semimetal for Spintronics: A Case Study of a Layered Square Net System EuZnSb$_2$

We use the first principles and effective Hamiltonian methods to study the electronic structure and magnetic properties of a recently synthesized layered antiferromagnetic square net topological semimetal EuZnSb$_2$ [1]. The main message of the paper is that effects of small changes in the band structure produced by the magnetic ordering and changes in the orientation of the \Neel vector are amplified in such transport properties as the spin Hall conductivity. We predict that the effects of the broken symmetry introduced by the ordering of the \Neel vector, being very weak in the bulk, are pronounced in the surface electronic dispersion, suggesting that surface probes may be more suited to measure them. The coexistence of the magnetism with many other competing phases make this material interesting and possibly useful for quantum spintronics applications.