  Magneto-optical effect has been widely used in light modulation, optical
sensing and information storage. Recently discovered two-dimensional (2D) van
der Waals layered magnets are considered as promising platforms for
investigating novel magneto-optical phenomena and devices, due to the
long-range magnetic ordering down to atomically-thin thickness, rich species
and tunable properties. However, majority 2D antiferromagnets suffer from low
luminescence efficiency which hinders their magneto-optical investigations and
applications. Here, we uncover strong light-magnetic ordering interactions in
2D antiferromagnetic MnPS3 utilizing a newly-emerged near-infrared
photoluminescence (PL) mode far below its intrinsic bandgap. This ingap PL mode
shows strong correlation with the Neel ordering and persists down to monolayer
thickness. Combining the DFT, STEM and XPS, we illustrate the origin of the PL
mode and its correlation with Neel ordering, which can be attributed to the
oxygen ion-mediated states. Moreover, the PL strength can be further tuned and
enhanced using ultraviolet-ozone treatment. Our studies offer an effective
approach to investigate light-magnetic ordering interactions in 2D
antiferromagnetic semiconductors.
