Transition metal dichalcogenide (TMD) based moiré materials have been shown to host various correlated electronic phenomena including Mott insulating states and fractional filling charge orders, quantum spin Hall effects, and (fractional) quantum anomalous Hall effects. To describe the low-energy states of long-wavelength moiré superlattice, we introduced the concept of moiré quantum chemistry, and developed transfer learning based large-scale first principle methods. In twisted bilayer TMD, we proposed the Mott ferroelectricity, kinetic magnetism and pseudogap metal from spin polarons. The pseudogap metal phase emerges at small doping below half filling and an intermediate range of fields, which exhibits a single-particle gap and a doping-dependent magnetization plateau.

I will also discuss the fractional quantum anomalous Hall effect in twisted homobilayer and its competing states. This series of works reveal the rich physics of semiconductor moiré superlattices as manifested in a variety of correlated and topological states. 

About the speaker:

Dr. Yang Zhang is an assistant professor in physics at the University of Tennessee, Knoxville, and visiting professor at Max Planck Institute Dresden. He received his BE degree from Tsinghua University and Ph.D. in Physics from Max Planck Institute Dresden, then he worked as a postdoc at MIT. His research interest lies in understanding the correlated/topological states, quantum transport, and light-matter interaction in quantum materials. Yang has received several awards, including the Tschirnhaus Medal from the Leibniz Association, and the Otto-Hahn Medal of the Max Planck Society.