Topological and Stacked Flat Bands in Bilayer Graphene with a Superlattice Potential.
Phys Rev Lett
; 130(19): 196201, 2023 May 12.
Article
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| MEDLINE
| ID: mdl-37243639
ABSTRACT
We show that bilayer graphene in the presence of a 2D superlattice potential provides a highly tunable setup that can realize a variety of flat band phenomena. We focus on two regimes (i) topological flat bands with nonzero Chern numbers, C, including bands with higher Chern numbers |C|>1 and (ii) an unprecedented phase consisting of a stack of nearly perfect flat bands with C=0. For realistic values of the potential and superlattice periodicity, this stack can span nearly 100 meV, encompassing nearly all of the low-energy spectrum. We further show that in the topological regime, the topological flat band has a favorable band geometry for realizing a fractional Chern insulator (FCI) and use exact diagonalization to show that the FCI is in fact the ground state at 1/3 filling. Our results provide a realistic guide for future experiments to realize a new platform for flat band phenomena.
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MEDLINE
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En
Revista:
Phys Rev Lett
Año:
2023
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Article
País de afiliación:
Estados Unidos