The magic and physics of twisted bilayer graphene

26/03/2019 @ 9:30 AM – 10:30 AM Asia/Singapore Timezone
S16 Level 6 – Theory Common Conference Room

Speaker: Dr Noah Fanqi Yuan
Affiliation: Department of Physics, Massachusetts Institute of Technology
Host: Professor Shaffique Adam
Location: Click HERE for directions

Abstract Details: 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 effects and other superlattices will be discussed.

About the Speaker: I got my Ph. D. in The Hong Kong University of Science and Technology in 2017, and now work as a
postdoc in Liang Fu’s group at MIT.
I’m mainly interested in superconductivity and topological phases in 2D materials. During my Ph. D.
research, I studied topological superconductors, Majorana zero modes, and spin-orbit coupling effect in
superconductivity (so-called Ising superconductivity).
Currently I’m interested in the unconventional superconducting and correlated insulating phases in
twisted bilayer graphene and other related systems.

1. Noah F. Q. Yuan, Hiroki Isobe, Liang Fu, Magic of high-order van Hove singularity, arXiv:
1901.05432 (2019).
2. Noah F. Q. Yuan and 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. Noah F. Q. Yuan, Wen-Yu He, K. T. Law, Superconductivity-Induced Ferromagnetism and Weyl
Superconductivity in Nb-doped Bi2Se3, Phys. Rev. B 95, 201109(R) (2017).
6. Junying Shen , Wen-Yu He , Noah F. Q. Yuan , Zengle Huang , Seng Huat Lee , Yew San Hor , Kam
Tuen Law , Chang-woo Cho and Rolf Lortz, Nematic topological superconducting phase in Nb-doped
Bi2Se3, npj Quantum Materials 2, 59 (2017).
7. Benjamin T. Zhou, Noah F. Q. Yuan, Hong-Liang Jiang, and K. T. Law, Ising Superconductivity and
Majorana Fermions in Transition Metal Dichalcogenides, Phys. Rev. B 93, 180501(R) (2016).
8. J. M. Lu, O. Zeliuk, I. Leermakers, Noah F. Q. Yuan, U. Zeitler, K. T. Law, J. T. Ye, Evidence for
two-dimensional Ising superconductivity in gated MoS2, Science 350, 1353 (2015).
9. Noah F. Q. Yuan, Kin Fai Mak, and K. T. Law, Possible Topological Superconducting Phases of
MoS2, Phys. Rev. Lett. 113, 097001 (2014).