Search for an Antiferromagnetic Weyl Semimetal in (MnTe)m(Sb2Te3)n and (MnTe)m(Bi2Te3)n Superlattices

The interaction between topology and magnetism can lead to novel topological materials including Chern insulators, axion insulators, and Weyl semimetals. Following a systematic first principles analysis of the superlattice structures based on MnTe and Sb2Te3 building blocks [i.e., (MnTe)m(Sb2Te3)n], we predict that an antiferromagnetic Weyl semimetal (WSM) exists within a van derWaals layered material. This centrosymmetric material, Mn10Sb8Te22, shows ferromagnetic intralayer and antiferromagnetic interlayer interactions. The obtained electronic bandstructure also indicates that the spin-split bands consistent with a WSM exist with a single pair of Weyl points. The presence of the Weyl nodes is subsequently verified with Berry curvature, Wilson loop, and Weyl chirality calculations. More specifically, Mn10Sb8Te22 is a van der Waals magnetic material consisting of three layers of MnSb2Te4 (i.e., m=1, n=1) and one layer of Mn7Sb2Te10 (i.e., m=7, n=1). In turn, Mn7Sb2Te10 is constructed by adding six layers of MnTe to MnSb2Te4. Other combinations of the MnSbTe-family materials are found to be antiferromagnetic topological or normal insulators on either side of the Mn:Sb ratio, respectively, illustrating the topological phase transition as anticipated. A similar investigation in the homologous (MnTe)m(Bi2Te3)n system produces mostly non-trivial antiferromagnetic insulators due to the strong spin-orbit couplig. When realized, the antiferromagnetic WSMs in the simplest form (i.e., a single pair of Weyl nodes) are expected to provide a promising candidate for low-power spintronic applications.