**4. Conclusion**

In summary, the recently developed 2D magnets and their novel photo-physical phenomena have been briefly summarized in this chapter. Firstly, we introduced the crystal structures, magnetic properties, and electronic band structures of several hot 2D magnets like CrX3 (X = Cl, Br, I), MPS3 (M = Fe, Ni, Mn), CrSBr and CrPS4. Then, according to these features, they exhibited novel light absorption, emission and scattering properties. More importantly, 2D magnets provide us a platform to tune the magnetic, electronic, and vibrational degrees of freedom for designing novel 2D magnet-based device applications. Although great processes have been made in this booming field in the past few years, the research on exploring light-matter interactions in 2D magnets is still in its infancy. There are many aspects that need researchers to further explore: growth of new 2D magnets, fabrication 2D magnetic heterostructures, development of advanced optical characterization techniques, and applying various state-of-the-art external perturbations for effectively engineering, et al. In essence, 2D magnets offer us an entirely new opportunity to explore novel photo-physical phenomena, therein looking promising for many more exciting outcomes shortly.
