Topological and thermoelectric potential of pnictogen-based double antiperovskites

In spite of several known classes of topological insulators, the search for new ones continue, primarily because most are not insulating enough in the bulk to allow study of their surface bands, nor to consider the anticipated applications. The band gap without spin-orbit coupling (SOC) must be small enough that band inversion can be driven by SOC, but large enough to inhibit bulk conductivity and enable application at room temperature. We present a broad study of pnictide-based double antiperovskites focusing on X₆AA'B₂ materials where X atoms are alkaline earth elements, and A and B are pnictogen atoms. Density functional calculations show that these semiconducting band gaps can be larger than that of corresponding single perovskites, for which we have provided a survey of 75 possibilities[1]. While useful topological characteristics will be difficult to realize, our results indicate that members in this class may be useful in thermoelectric applications.

[1] W. F. Goh and W. E. Pickett, Survey of the class of isovalent antiperovskite alkaline earth-pnictide compounds, arXiv:1710.10716.