Engineering magnetic topological insulators in Eu$_5M_2X_6$ Zintls

Abstract

Magnetic topological insulator provide a prominent material platform for quantum anomalous Hall physics and axion electrodynamics. However, the lack of material realizations with cleanly gapped surfaces hinders technological utilization of these exotic quantum phenomena. Here, using the Zintl concept and the properties of non-symmorphic space groups, we computationally engineer magnetic topological insulators. Specifically, we explore Eu5M2X6 (M =metal, X =pnictide) Zintl compounds and find that Eu5Ga2Sb6, Eu5Tl2Sb6 and Eu5In2Bi6 form stable structures with nontrivial Z2 indices. We also show that epitaxial and uniaxial strain can be used to control the Z2 index and the bulk energy gap. Finally, we discuss experimental progress towards the synthesis of the proposed candidates and provide insights that can be used in the search for robust magnetic topological insulators in Zintl compounds.