Title: Correlated electronic states in moiré superlattices of transition metal dichalcogenides

Speaker: Yongtao Cui (University of California, Riverside)

Time: 14:00 pm, Friday, July 21th, 2023

Location: Lecture Hall C302, Department of Physics

Abstract: Moiré superlattices formed by angle-aligned multilayer stacks of 2D materials have recently become a rich platform to discover novel electronic states, such as superconductivity, correlated insulators, and magnetism. In this talk, I will talk about our recent work on the study of correlated states in moiré superlattices of semiconducting transition metal dichalcogenides monolayers. We employ scanning microwave impedance microscopy to probe the local conductivity of these moiré superlattices. We find that correlated insulating states can appear when the moiré superlattice is partially filled with carriers at simple fractional fillings. When additional layers are introduced in the moiré structure, we find that the correlated states can be manipulated in various ways. By applying an electric field, the carriers can be driven to populate in two different layers yet still form insulating states, which can be interpreted as an excitonic insulator. We perform a combination of optical spectroscopy and scanning probe microscopy measurements to reveal the nature of this state.

Biography: Dr. Yongtao Cui is an Associate Professor in the Department of Physics and Astronomy at the University of California, Riverside. He obtained his B.S. in Physics from Peking University in 2005, and his PhD degree in Applied Physics from Cornell University in 2012. He then moved to Stanford University for postdoc research on the development of Microwave Impedance Microscopy and applying it to the study of nanoscale electronic states in quantum materials. He joined UC Riverside in the summer of 2016. His group is interested in the study of electronic and magnetic states in 2D materials with scanning probe microscopy techniques.