Merkl, P. and Mooshammer, F. and Steinleitner, P. and Girnghuber, A. and Lin, K. -Q. and Nagler, P. and Holler, J. and Schueller, C. and Lupton, J. M. and Korn, T. and Ovesen, S. and Brem, S. and Malic, E. and Huber, R. (2019) Ultrafast transition between exciton phases in van der Waals heterostructures. NATURE MATERIALS, 18 (7). 691-+. ISSN 1476-1122, 1476-4660
Full text not available from this repository. (Request a copy)Abstract
Heterostructures of atomically thin van der Waals bonded monolayers have opened a unique platform to engineer Coulomb correlations, shaping excitonic(1-3), Mott insulating(4) or superconducting phases(5,6). In transition metal dichalcogenide heterostructures(7), electrons and holes residing in different monolayers can bind into spatially indirect excitons(1,3,8-11) with a strong potential for optoelectronics(11,12), valleytronics(1,3,13), Bose condensation(14), superfluidity(14,15) and moire-induced nanodot lattices(16). Yet these ideas require a microscopic understanding of the formation, dissociation and thermalization dynamics of correlations including ultrafast phase transitions. Here we introduce a direct ultrafast access to Coulomb correlations between monolayers, where phase-locked mid-infrared pulses allow us to measure the binding energy of interlayer excitons in WSe2/WS2 hetero-bilayers by revealing a novel 1s-2p resonance, explained by a fully quantum mechanical model. Furthermore, we trace, with subcycle time resolution, the transformation of an exciton gas photogenerated in the WSe2 layer directly into interlayer excitons. Depending on the stacking angle, intra- and interlayer species coexist on picosecond scales and the 1s-2p resonance becomes renormalized. Our work provides a direct measurement of the binding energy of interlayer excitons and opens the possibility to trace and control correlations in novel artificial materials.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | INDIRECT INTERLAYER EXCITONS; GRAPHENE; DYNAMICS; |
| Subjects: | 500 Science > 530 Physics |
| Divisions: | Physics > Institute of Experimental and Applied Physics > Chair Professor Lupton > Group John Lupton |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 08 Apr 2020 05:19 |
| Last Modified: | 08 Apr 2020 05:19 |
| URI: | https://pred.uni-regensburg.de/id/eprint/26782 |
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