Date and Time: 26-July-2024（Friday）10:30am (Beijing time)

Venue: Room 320

Speaker: Yuchi He，Postdoctoral Researcher, University of Oxford

Host: Chuanchang Zeng ( BAQIS)

Title: Strongly correlated physics in twisted bilayer transition metal dichalcogenides

About the Speaker:

Yuchi He obtained his PhD in the physics department of Carnegie Mellon University, USA in 2020. Before that, he got his BS in Peking University. He worked as a postdoc in RWTH Aachen University and now work in the University of Oxford. His primary research interest is phases and dynamics of strongly correlated quantum many-body systems. One-dimensional and two-dimensional systems are investigated by application and development of effective field theory and tensor networks. Most recently, he is interested in twisted transition metal dichalcogenides and driven-dissipative systems.

Abstract:

The investigation of twisted bilayer graphene has opened a “twistronics era”, providing unprecedented tunability for solid-state systems and an excellent platform for strongly correlated quantum phases and their transitions. While twisted bilayer graphene requires involved multi-band descriptions, twisted bilayer transition metal dichalcogenides are simpler. In this talk, I will introduce some of our theoretical works as well as have a brief review of some of the most recent experimental progress.

We studied two cases of twisted bilayer transition metal dichalcogenides: (1) effective triangular systems and (2) effective honeycomb systems. For triangular systems, we study possible magnetic orders and spin liquids at half-filling; we also study the magnetic orders at the van Hove filling, providing an explanation for the absence of the predicted quantum anomalous Hall effect in experiments. For honeycomb systems, we numerically reveal integer and fractional quantum anomalous Hall effects, providing theoretical support for the ground-breaking experimental discovery of fractional quantum anomalous Hall effects. I will briefly review recent experimental works on twisted MoTe2 and WSe2 which show consistency with our predictions.