CaSTL Seminar with Shiwei Wu

Molybendum disulphide along with other transition metal dichalcogenides has emerged as another star in the family of atomically thin two dimensional materials. Different from its bulk counterpart, few-layer MoS₂ has appreciable variations in the electronic band structures, and evolves into a direct bandgap semiconductor when it is thinned down to a monolayer form. Furthermore, few-layer MoS₂ exhibits oscillatory structural symmetry with odd layer having inversion symmetry broken and even layer recovering its inversion symmetry. Combined with the reduced dimensionality, these fundamental characteristics have enabled many intriguing and novel phenomena for applications in optoelectronics and valleytronics. In this talk, I will present some of our recent findings in this wonder material by using nonlinear optical microscopy and spectroscopy. The rapid progress in this area has also called for the development of optics-combined scanning tunnelling microscopy with simultaneously high spatial, spectral and temporal resolution. I will describe the efforts by my research group at Fudan University at the end of the talk.