Giant Magneto-Optical Schäfer-Hubert Effect in Two-Dimensional van der Waals Antiferromagnets $\mathit{\text{M}}$PS${}_3$ ($\mathit{\text{M}}$=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 Schäfer-Hubert effect (MOSHE) in 2D vdW antiferromagnetic $\mathit{\text{M}}$PS${}_3$ ($\mathit{\text{M}}$ = 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 non-magnetic substrate. The MOSHE of monolayer and bilayer $\mathit{\text{M}}$PS${}_3$ are considerably large ($>2^{\circ }$), originating from the strong anisotropy of in-plane optical conductivity. The Schäfer-Hubert rotation angles are surprisingly insensitive to the orientations of the Néel vector, while the Schäfer-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 $\mathit{\text{M}}$PS${}_3$ family in antiferromagnetic nanophotonic devices.