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Magic angles and high Chern number flat band of a twisted multilayer graphene model

Early Career Math Colloquium

Magic angles and high Chern number flat band of a twisted multilayer graphene model
Series: Early Career Math Colloquium
Location: Online
Presenter: Mengxuan Yang, UC Berkeley

In condensed matter physics, when two or more sheets of graphene are twisted by certain angles, a.k.a. magic angles, the resulting material becomes superconducting. The mathematics behind this is a blend of basic representation theory, Bloch-Floquet theory, Jacobi theta functions and holomorphic line bundles. In this talk, I will compare a chiral multilayer graphene (TMG) model with the chiral twisted bilayer graphene (TBG) model studied by Tarnopolsky--Kruchkov--Vishwanath and Becker--Embree--Wittsten--Zworski to show that magic angles of TMG are the same with magic angles of TBG. I will also present a band separation due to the interlayer tunneling by setting up a Grushin problem. Finally, I will present a construction of a holomorphic line bundle with Chern number $-n$. The high Chern number band attracts many attentions in physics for its role in both integer, fractional quantum Hall effect and fractional Chern insulators.

https://arizona.zoom.us/j/85705568785