Group Meetings Schedule 2024
Jan 29, Sayan Choudhury, Monday 9:00 am Pitt time (10:00 PM Beijing time)
Feb 7, Simon Shi, Wednesday 8:30 pm Pitt time (Thu, Feb 8, 9:30 AM Beijing time)
Title: Magic of Topological Moiré Bands — Fractional and Integer Quantum Anomalous Hall Effects
Abstract: Moiré superlattices are exciting platforms to study interaction-driven exotic phases of matter. I will mainly present my recent doctoral work motivated by the observation of fractional quantum anomalous Hall effect in twisted homobilayer transitional metal dichalcogenides. An adiabatic approximation, which maps the moiré bands to a hole gas in a nonuniform periodic pseudo-magnetic field and a periodic potential, has been proposed to explain the occurrence of the flat band and ideal quantum geometry. We show that the adiabatic approximation is accurate under realistic conditions, and that the ideal quantum geometry arises from a partial Aharonov-Casher cancellation between the magnetic field and the potential. Interestingly, higher-shell Fourier components of the residual potential do not strongly violate the ideal quantum geometry though they do change wave functions. Next, I will briefly present my earlier work on twisted bilayer graphene aligned with hexagonal boron nitride (hBN), in which we propose that the appearance or absence of quantum anomalous Hall effect depends on the commensurability between the two moiré patterns, one between the two graphene layers and the other between the hBN and its adjacent graphene layer.
Feb 14, Nikolay Yegovtsev, Wednesday 8:30 pm Pitt time (Thu, Feb 15, 9:30 AM Beijing time)
Daylight Savings Time Starts
Mar 13, Hongyu Wang, Wednesday 9:00 pm Pitt time (Thu, Mar 14, 9:00 AM Beijing time)
Mar 27, Bao-Zong Wang, Wednesday 9:00 am Pitt time (Thu, Mar 28,9:00 AM Beijing time)
Apr 10, Xin-Chi Zhou, Wednesday 9:00 am Pitt time (Thu, Apr 11, 9:00 AM Beijing time)
Apr 24, Haoran Sun, Wednesday 9:00 am Pitt time (Thu, Apr 25, 9:00 AM Beijing time)
May 8, Adham Mahmoud Helmi, Wednesday 9:00 am Pitt time (Thu, May 9, 9:00 AM Beijing time)
May 22, Yi Peng, Wednesday 9:00 am Pitt time (Thu, May 23, 9:00 AM Beijing time)
