The multiple topological phases in a new family of compounds ACrTe (A = Na, K, Rb, Cs) predicted by first-principles calculations

Abstract

Based on first-principles calculations, we predict a new family of chromium-based compounds, ACrTe (A = Na, K, Rb, Cs), which share the same structure as the iron-based superconductor LiFeAs. We show that all these materials are narrow-gap antiferromagnetic (AFM) semiconductors. The AFM order is of the checkerboard type within Cr layers, while the interlayer coupling changes from ferromagnetic (FM) for NaCrTe to AFM for KCrTe, RbCrTe and CsCrTe. Interestingly, we find that the small gap is sensitive to in-plane biaxial strain and magnetic fields, which can tune the bulk compounds to become Dirac and Weyl semimetals and tune the monolayer case to exhibit quantum spin and anomalous Hall effects. Significantly, both Dirac and Weyl semimetals show clean topological structures with a long-sought single pair of Dirac and Weyl points at the Fermi level. Our studies may provide an ideal candidate material to study Dirac and Weyl physics and to realize clean quantum spin and anomalous Hall effects.