Lin, Kai-Qiang and Faria, Paulo E. and Bauer, Jonas M. and Peng, Bo and Monserrat, Bartomeu and Gmitra, Martin and Fabian, Jaroslav and Bange, Sebastian and Lupton, John M. (2021) Twist-angle engineering of excitonic quantum interference and optical nonlinearities in stacked 2D semiconductors. NATURE COMMUNICATIONS, 12 (1): 1553. ISSN 2041-1723
Full text not available from this repository. (Request a copy)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 235meV by twisting, with a twist-angle susceptibility of 8.1meV/degrees, 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. Here, the authors report on the large twist-angle susceptibility of excitons involving upper conduction bands in transition metal dichalcogenide bilayers. These high-lying excitons couple with band-edge excitons, and give rise to nonlinear quantum-optical processes that become tuneable by twisting.
| Item Type: | Article |
|---|---|
| Subjects: | 500 Science > 530 Physics |
| Divisions: | Physics > Institute of Theroretical Physics > Chair Professor Richter > Group Jaroslav Fabian Physics > Institute of Experimental and Applied Physics > Chair Professor Lupton > Group John Lupton |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 17 Aug 2022 09:14 |
| Last Modified: | 17 Aug 2022 09:14 |
| URI: | https://pred.uni-regensburg.de/id/eprint/46527 |
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