**3. Light-mater interactions in 2D magnets**

vdWs layered materials offer fascinating opportunities for studying light-matter interactions in the 2D limit. So far, many interesting optical phenomena have been observed in monolayer semiconducting TMDs and other non-metallic 2D materials. However, none of these 2D materials possesses long-range magnetic order. The discovery of 2D system hosting intrinsic magnetic order represents a seminal addition to the rich landscape of vdW materials. More importantly, the interdependence of structure and magnetism, along with strong light-matter interactions, provides a new platform to explore the optical control of magnetic, electronic, and vibrational degrees of freedom at the 2D limit. Here, we briefly summarize the optical properties of several 2D magnets that have been studied in recent years. The correlation between emitted photons, phonons and spins (magnetic orders) in layered magnets provides routes for investigating magneto-optics in 2D materials, and hence opens a path for developing opto-spintronic devices and AFM/FM-based quantum information technologies.
