Bulletin of the American Physical Society
APS March Meeting 2021
Volume 66, Number 1
Monday–Friday, March 15–19, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session B49: Chern Insulators in Topological Flat bands: Twisted Bilayer Graphene and Beyond
11:30 AM–2:30 PM,
Monday, March 15, 2021
Sponsoring Unit: DCMP
Chair: Eva Andrei, Rutgers University, New Brunswick
Abstract: B49.00002 : Correlations and topology in the magic angle twisted bilayer graphene
12:06 PM–12:42 PM
(Florida State Univ)
(Florida State Univ)
In the second part of the talk, I will present a two stage renormalization group treatment  which connects the continuum Hamiltonian at length scales shorter than the moire superlattice period to the Hamiltonian for the active narrow bands only, which is valid at distances much longer than the moire period. Via a progressive numerical elimination of remote bands the relative strength of the one-particle-like dispersion and the interactions within the active narrow band Hamiltonian will be determined, thus quantifying the residual correlations and justifying the strong coupling approach in the final step.
In the last part of the talk, the states favored by electron-electron Coulomb interactions within the narrow bands will be discussed. Analytical and DMRG results based on 2D localized Wannier states [2,5], 1D localized hybrid Wannier states  and Bloch states [3,4] will be compared. Topological and symmetry constraints on the spectra of charged and neutral excitation for various ground states, as well as non-Abelian braiding of Dirac nodes , will also be presented.
 Jian Kang and Oskar Vafek, Phys. Rev. X 8, 031088 (2018).
 Jian Kang and Oskar Vafek, Phys. Rev. Lett. 122, 246401 (2019)
 Jian Kang and Oskar Vafek, Phys. Rev. B 102, 035161 (2020)
 Oskar Vafek and Jian Kang arXiv:2009.09413 (to appear in PRL)
 Bin-Bin Chen, Yuan Da Liao, Ziyu Chen, Oskar Vafek, Jian Kang, Wei Li, Zi Yang Meng arXiv:2011.07602
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