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Twist-angle engineering of excitonic quantum interference and optical nonlinearities in stacked 2D semiconductors

Published version
Peer-reviewed

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Authors

Lin, Kai-Qiang 
Faria Junior, Paulo E. 
Bauer, Jonas M. 
Monserrat, Bartomeu  ORCID logo  https://orcid.org/0000-0002-4233-4071

Abstract

Abstract: Twist-engineering of the electronic structure in van-der-Waals layered materials relies predominantly on band hybridization between layers. Band-edge states in transition-metal-dichalcogenide semiconductors are localized around the metal atoms at the center of the three-atom layer and are therefore not particularly susceptible to twisting. Here, we report that high-lying excitons in bilayer WSe2 can be tuned over 235 meV by twisting, with a twist-angle susceptibility of 8.1 meV/°, an order of magnitude larger than that of the band-edge A-exciton. This tunability arises because the electronic states associated with upper conduction bands delocalize into the chalcogenide atoms. The effect gives control over excitonic quantum interference, revealed in selective activation and deactivation of electromagnetically induced transparency (EIT) in second-harmonic generation. Such a degree of freedom does not exist in conventional dilute atomic-gas systems, where EIT was originally established, and allows us to shape the frequency dependence, i.e., the dispersion, of the optical nonlinearity.

Description

Keywords

Article, /639/624/400/385, /639/766/119/1000/1018, /140/125, article

Journal Title

Nature Communications

Conference Name

Journal ISSN

2041-1723

Volume Title

12

Publisher

Nature Publishing Group UK
Sponsorship
Deutsche Forschungsgemeinschaft (German Research Foundation) (314695032, 443378379)
Alexander von Humboldt-Stiftung (Alexander von Humboldt Foundation) (99999.000420/2016-06)