Tuning Strongly Correlated States and Quantum Phase Transitions in a Moiré Superlattice

by Prof. Wei Yang

Monday 28 Apr 2025, 10:00 → 11:00 Asia/Shanghai

Tsung-Dao Lee Institute/N6F-N601 - Meeting Room (Tsung-Dao Lee Institute)

Host: Prof. Haibiao Zhou

Venue: TDLI Meeting Room N601

Tencent meeting link:  https://meeting.tencent.com/dm/hAtn5nZrokVM    Meeting ID:  390538115, no password

 

Abstract:

A new phase of matter usually emerges when a given symmetry breaks spontaneously, which can involve charge, spin, valley, and layer degrees of freedom. Twisting graphene multilayer to form a moiré superlattice leads to moiré flat bands where various correlated states are developed. Twisted double bilayer graphene (TDBG) is an electrical displacement field (D) tunable moiré system. Here, I will focus on the high-quality ABBA-stacked TDBG device and present the experimental observations of various correlated phases, such as spin/valley/layer polarized phases, where interplays among correlation, isospin polarization, topology, and scatterings are important. If time permits, I will discuss the emergence of heavy fermion features in the strongly correlated regime and novel chiral topological phases at the quantum phase transitions. 

 

Biography:

Wei Yang is an associate professor at the Institute of Physics, Chinese Academy of Sciences (IOP-CAS) in Beijing, China. He received his Ph.D in condensed matter physics from IOP-CAS in 2014, working on graphene-hBN superlattice. He worked as a postdoc from 2014 to 2019, first at École Normale Supérieure and CNRS in Paris on high-frequency noise thermometry, then at ICOF-The Institute of Photonic Sciences in Barcelona on quantum transport and nano-mechanics of carbon nanotube. He joined the IOP-CAS as a faculty member in 2019. Currently, he mainly focuses on exploring strongly correlated phases and quantum phase transitions in moiré superlattices.