Peter Grünberg Colloquium - Extraordinary Talk: Prof. Dr. Shiwei Wu, Fudan University, Shanghai, China

Please note: You will receive the link to the online talk in the e-mail invitation, usually sent out a few days before the lecture takes place. It is also available on request.

Nonlinear magneto-optical effect in 2D magnets

The magneto-optical effects are known as an indispensable tool for studying condensed matter physics in quantum materials. In the past, attention has been paid to the linear magneto-optical effects such as the Faraday rotation, Kerr rotation, and magnetic circular dichroism. In this talk, I will introduce the nonlinear magneto-optical effects based on the optical second harmonic generation process, including the nonreciprocal second harmonic generation (SHG) contributed by magnetic structures and the nonlinear Kerr rotation effect formed by the coherent superposition of lattice and magnetic contributions. Compared to the linear Faraday/Kerr rotations that are only sensitive to non-zero magnetization in ferromagnetic materials, the nonlinear magneto-optical effects are more versatile and particularly powerful for anti-ferromagnetic materials. Recently we found the layered anti-ferromagnetism in CrI₃ bilayer leads to a giant nonreciprocal SHG, three orders of magnitude larger than that in bulk magnetic crystals [Nature 572, 497 (2019)]. Here I will report our latest studies on various two-dimensional magnetic materials and the underlying physics.