Article Control of the valley polarization of monolayer WSe2 by Dexter-like coupling

Jakub Jasiński ; Joshua J P Thompson ; Swaroop Palai ; Maciej Śmiertka ; Mateusz Dyksik ; Takashi Taniguchi SAMURAI ORCID (National Institute for Materials Science) ; Kenji Watanabe SAMURAI ORCID (National Institute for Materials Science) ; Michał Baranowski ; Duncan K Maude ; Alessandro Surrente ; Ermin Malic ; Paulina Płochocka

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Jakub Jasiński, Joshua J P Thompson, Swaroop Palai, Maciej Śmiertka, Mateusz Dyksik, Takashi Taniguchi, Kenji Watanabe, Michał Baranowski, Duncan K Maude, Alessandro Surrente, Ermin Malic, Paulina Płochocka. Control of the valley polarization of monolayer WSe2 by Dexter-like coupling. 2D Materials. 2024, 11 (2), 025007.
SAMURAI

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(abstract)

Intervalley scattering mechanisms govern the dynamics of excitonic complexes in transition metal dichalcogenide monolayers. Here, we investigate the excitation energy dependence of the valley polarization of excitons in a WSe2 monolayer. We observe that the valley polarization drastically decreases when the excitation is resonant with the B1s resonance. This behaviour can be explained by a Dexter-like coupling in the momentum space between exciton states residing in opposite valleys but with the same spin configuration. This induces a net transfer of the exciton population from the optically driven valley towards the opposite, undriven valley. We observe the long-term fingerprints of this population transfer, as a vanishing valley polarization for the neutral exciton, and a negative valley polarization for biexcitonic complexes, in qualitative agreement with theoretical predictions based on a fully microscopic many-particle approach. This, together with a decrease of the PL energy when the excitation is resonant with the B1s state, points to the prominent role of the Dexter-like coupling in the exciton dynamics of atomically thin semiconductors.

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Keyword: Intervalley scattering, excitonic complexes, WSe2

Date published: 2024-04-01

Publisher: IOP Publishing

Journal:

  • 2D Materials (ISSN: 20531583) vol. 11 issue. 2 025007

Funding:

  • Narodowe Centrum Nauki 2020/38/E/ST3/00194
  • Japan Society for the Promotion of Science 19H05790
  • Agence Nationale de la Recherche Programme des Investissement d’Avenir
  • Deutsche Forschungsgemeinschaft CRC 1083

Manuscript type: Publisher's version (Version of record)

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First published URL: https://doi.org/10.1088/2053-1583/ad1ae8

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Updated at: 2025-02-26 08:30:22 +0900

Published on MDR: 2025-02-26 08:30:22 +0900

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