Enhancing ferromagnetic coupling in CrXY (X = O, S, Se; Y = Cl, Br, I) monolayers by turning the covalent character of Cr-X bonds

This paper investigates the electronic and magnetic properties of 1T phase chromium sulfide halide CrXY (X = O, S, Se; Y = Cl, Br, I) monolayers using first-principles calculations. All CrXY monolayers except CrOl are stable ferromagnetic semiconductors. Ferromagnetic coupling is primarily driven by kinetic exchange between Cr's empty e-orbital and anions' p-orbital. The coupling strength is enhanced by increasing the covalent contribution of Cr-X bonds, which is achieved by minimizing the energy difference between coupled orbitals. Substituting O with S/Se triples the Curie temperature (Tc), reaching a maximum of 334 K in CrSeI. High stability and Tc suggest suitability for 2D spintronic devices.

Hao-Ran Zhu, Bin Shao, Xu Zuo