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Hybridized intervalley moiré excitons and flat bands in twisted WSe2 bilayers
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Kai-Qiang Lin ,
Roland Gillen ,
Jonas M. Bauer,
Janina Maultzsch,
John M. Lupton,
Ermin Malic
Nanoscale, Volume: 12, Issue: 20, Pages: 11088 - 11094
Swansea University Author:
Roland Gillen
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DOI (Published version): 10.1039/d0nr02160a
Abstract
The large surface-to-volume ratio in atomically thin 2D materials allows to efficiently tune their properties through modifications of their environment. Artificial stacking of two monolayers into a bilayer leads to an overlap of layer-localized wave functions giving rise to a twist angle-dependent...
| Published in: | Nanoscale |
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| ISSN: | 2040-3364 2040-3372 |
| Published: |
Royal Society of Chemistry (RSC)
2020
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| Online Access: |
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| URI: | https://cronfa.swan.ac.uk/Record/cronfa66659 |
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| Abstract: |
The large surface-to-volume ratio in atomically thin 2D materials allows to efficiently tune their properties through modifications of their environment. Artificial stacking of two monolayers into a bilayer leads to an overlap of layer-localized wave functions giving rise to a twist angle-dependent hybridization of excitonic states. In this joint theory-experiment study, we demonstrate the impact of interlayer hybridization on bright and momentum-dark excitons in twisted WSe2 bilayers. In particular, we show that the strong hybridization of electrons at the Λ point leads to a drastic redshift of the momentum-dark K–Λ exciton, accompanied by the emergence of flat moiré exciton bands at small twist angles. We directly compare theoretically predicted and experimentally measured optical spectra allowing us to identify photoluminescence signals stemming from phonon-assisted recombination of layer-hybridized dark excitons. Moreover, we predict the emergence of additional spectral features resulting from the moiré potential of the twisted bilayer lattice. |
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| College: |
Faculty of Science and Engineering |
| Funders: |
The Chalmers group acknowledges financial support from the European Unions Horizon 2020 research and innovation program under grant agreement no 785219 (Graphene Flagship) as well as from the Swedish Research Council (VR, project number 2018-00734). The Regensburg group acknowledges financial support from Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – Project-ID 314695032 – SFB 1277 project B03. The Erlangen group acknowledges the Regional Computer Centre Erlangen (RRZE) for providing the computational resources for the DFT simulations. |
| Issue: |
20 |
| Start Page: |
11088 |
| End Page: |
11094 |