Two-sublattice double exchange driven magnetism in Cr-based two-dimensional magnets

Focusing on the recently discussed two-dimensional (2D) ferromagnetic compound, CrSBr, with a larger than 100 K transition temperature, we analyze its unusual electronic structure using a combination of numerical techniques. Our findings indicate magnetism to be driven by a two-sublattice double exchange mechanism. Our results reproduce the large magnetic transition temperature of CrSBr, as well as the significantly suppressed transition temperature in the related compound, ${\mathrm{CrPS}}_{4}$. The same mechanism rationalizes the observed negative, hysteretic magnetoresistance in bilayer CrSBr. Based on the discussed mechanism, we predict that the magnetic transition temperature may be further increased for the 2D semiconducting magnet CrSeBr and 2D metallic magnet CrTeBr.