Time: 10:00am, May 6 (Mon.), 2019

Venue: Room N406, UCAS Teaching Building [View Map]

Speaker: Dr. Noah Fan-Qi Yuan (MIT)

Abstract:      
Recently, unconventional superconducting phase and correlated insulating phase in twisted bilayer graphene have attracted a lot of attention, which occurs at specific fillings and within a narrow range of twist angles (so-called magic angle). In this talk, I would like to address the following questions.
1. What are the suitable models to describe the electronic states in twisted bilayer graphene?
2. Why is the  “magic angle” so special?
3. What are the possible superconducting and insulating phases at half filling?
Related topics such as strain effect and other superlattices will also be discussed.      

References:      
[1] Noah F. Q. Yuan, Hiroki Isobe, Liang Fu, Magic of high-order van Hove singularity, arXiv: 1901.05432 (2019).
[2] Noah F. Q. Yuanand Liang Fu, Model for the metal-insulator transition in graphene superlattices and beyond, Phys. Rev. B 98, 045103 (2018). Editors’ Suggestion & Featured in Physics.
[3] M. Koshino, Noah F. Q. Yuan, T. Koretsune, M. Ochi, K. Kuroki, L. Fu, Maximally-localized Wannier orbitals and the extended Hubbard model for the twisted bilayer graphene, Phys. Rev. X 8, 031087 (2018).
[4] H. Isobe, Noah F. Q. Yuan, L. Fu, Superconductivity and Charge Density Wave in Twisted Bilayer Graphene, Phys. Rev. X 8, 041041 (2018).
[5] Zhen Bi, Noah F. Q. Yuan, L. Fu, Designning Flat Band by Strain, arXiv: 1902.10146 (2019).