New family of Dirac and Weyl semimetals in XAuTe (X = Na, K, Rb) ternary honeycomb compounds

Abstract

We propose a new family of 3D Dirac semimetals based on XAuTe (X = K, Na, Rb) ternary honeycomb compounds, determined based on first-principles calculations, which are shown to be topological Dirac semimetals in which the Dirac points are induced by band inversion. Dirac points with four-fold degeneracy that are protected by C3 rotation symmetry and located on the Γ -A high-symmetry path are found. Through spatial-inversion symmetry breaking, a K(Au0.5 Hg0.5)(Te0.5As0.5) superlattice structure composed of KHgAs and KAuTe compounds is proven to be a Weyl semimetal with type-II Weyl points, which connect electron- and hole-like bands. In this superlattice structure, the six pairs of Weyl nodes are distributed along the K- Γ high-symmetry path on the k z = 0 plane. Our research expands the family of topological Dirac and type-II Weyl semimetals.