Abstract
Using a multiscale computational approach, we probe the origin and evolution of ultraflat bands in moiré superlattices of twisted bilayer , a prototypical transition metal dichalcogenide. Unlike twisted bilayer graphene, we find no unique magic angles in twisted bilayer for flat-band formation. Ultraflat bands form at the valence band edge for twist angles () close to and at both the valence and conduction band edges for close to , and have distinct origins. For close to , inhomogeneous hybridization in the reconstructed moiré superlattice is sufficient to explain the formation of flat bands. For close to , additionally, local strains cause the formation of modulating triangular potential wells such that electrons and holes are spatially separated. This leads to multiple energy-separated ultraflat bands at the band edges closely resembling eigenfunctions of a quantum particle in an equilateral triangle well. Twisted bilayer transition metal dichalcogenides are thus suitable candidates for the realization of ordered quantum dot array.
10 More- Received 27 August 2019
- Revised 16 June 2020
- Accepted 20 July 2020
DOI:https://doi.org/10.1103/PhysRevB.102.075413
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