Electronic, magnetic, and topological properties of layered ternary chalcogenide CoAsS: A first principles study

Abstract

Quantum anomalous Hall effect with intrinsic magnetism in atomically thin 2D material has huge applications in nano-electronics and spintronics. A comprehensive comparative analysis of structural, electronic, and magnetic properties of transition metal ternary chalcogenide CoAsS has been carried out employing first principle calculations with density functional theory (DFT) and DFT+U methods. DFT+U calculation also shows intrinsic magnetization in both the bulk and monolayer of CoAsS, thus revealing rare phenomenon in van der Waals (vdW) layered material. It is observed that the most stable magnetic ordering is either antiferromagnetic (AFM) or ferromagnetic (FM) depending on the U value. At higher U, direct d-d exchange interactions dominate, leading to FM stability over the indirect superexchange interactions mediated by p orbitals of As and S responsible for AFM stability (for U<8.2 eV). A topological state is also found by computing a non-trivial Chern number in the FM phase of CoAsS monolayer. This highlights the significance of this material for realizing topological state for its potential applications in spintronics and nano-electronics.