Giant magneto-optical Schäfer-Hubert effect in the two-dimensional van der Waals antiferromagnets MPS3 ( M=Mn , Fe, Ni)

The recent discovery of long-range magnetic order in atomically thin films has triggered particular interest in two-dimensional (2D) van der Waals (vdW) magnetic materials. In this paper, we perform a systematic theoretical study of the magneto-optical Sch\"afer-Hubert effect (MOSHE) in 2D vdW antiferromagnetic $M{\mathrm{PS}}_{3}$ ($M=\mathrm{Mn}$, Fe, Ni) with multifold intralayer and interlayer magnetic orders. The formula for evaluating the MOSHE in 2D magnets is derived by considering the influence of a nonmagnetic substrate. The MOSHE of monolayer and bilayer $M{\mathrm{PS}}_{3}$ is very large ($>{2}^{\ensuremath{\circ}}$), originating from the strong anisotropy of in-plane optical conductivity. The Sch\"afer-Hubert rotation angles are surprisingly insensitive to the orientations of the N\'eel vector, while the Sch\"afer-Hubert ellipticities are identified to be a good criterion to distinguish different interlayer magnetic orders. Our work establishes a theoretical framework for exploring novel 2D vdW magnets and facilitates the promising applications of the 2D $M{\mathrm{PS}}_{3}$ family in antiferromagnetic nanophotonic devices.