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Jennifer Cano: Higher magic angles in twisted bilayer graphene and topological twistronics
January 27, 2022 @ 10:00 am - 11:00 am
Meeting ID: 684 7017 3961
Speaker: Jennifer Cano, Assistant Professor at Stony Brook University
Title: Higher magic angles in twisted bilayer graphene and topological twistronics
Bio: Jennifer Cano is an Assistant Professor at Stony Brook University and an Affiliate Associate Research Scientist at the Flatiron Institute. She earned a PhD in physics from the University of California, Santa Barbara, in 2015, and was subsequently a postdoctoral fellow at the Princeton Center for Theoretical Science. Her research is focused on the classification and realization of topological phases of matter, ranging from strongly correlated phases with fractionalized excitations to non-interacting topological band structures.
Abstract: We present recent analytical and numerical results on the chiral model of twisted bilayer graphene and introduce a new platform for twistronic devices on the surface of a topological insulator. In the first part of the talk, we study the flat band wavefunctions of chiral twisted bilayer graphene at higher magic angles. We show that at higher magic angles, the wavefunctions exhibit an increasing number of zeros, resembling quantum Hall wavefunctions at higher Landau levels. Zeros of the same chirality cluster near the center of the moire unit cell, causing an enhanced phase winding and circulating current. The wavefunctions at higher magic angles have signatures in scanning tunneling microscopy and orbital magnetization experiments. In the second half of the talk, we investigate the fate of the surface Dirac cone of a three-dimensional topological insulator subject to a superlattice potential. Using a combination of diagrammatic perturbation theory, lattice model simulations, and ab initio calculations, we report a dramatic renormalization of the surface Dirac cone velocity and the formation of gapless satellite Dirac cones. The latter can produce very flat bands that may be a fruitful place to searching for interaction-driven physics.