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02247nam a2200385Ia 4500 |
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10.1038-s41699-022-00303-x |
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|a 23977132 (ISSN)
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|a Imaging the effect of high photoexcited densities on valley polarization and coherence in MoS2 monolayers
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|b Nature Research
|c 2022
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|z View Fulltext in Publisher
|u https://doi.org/10.1038/s41699-022-00303-x
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|a We have investigated the laser-induced valley polarization and coherence of encapsulated MoS2 monolayer as a function of temperature, power density, and spatial position. Besides a non-monotonic dependence on temperature, recently attributed to a dependence of the valley relaxation time on the momentum scattering rate, we observe a two-fold increase of the valley polarization when increasing the laser excitation power. We attribute this effect to a local heating induced by the energy relaxation of photoexcited excitons and to an increase of the exciton-exciton scattering rate. In contrast, only a moderate enhancement of valley coherence is observed, which exhibits a dramatic drop after further increasing the excitation power. We attribute this behaviour to the detrimental role of exciton-exciton interactions on the pure dephasing rate responsible for the loss of coherence between the valleys. This manifests itself by a strong dip in the spatial profile of the valley coherence at high photoexcited densities. © 2022, The Author(s).
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|a Energy relaxation
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|a Excitation power
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|a Exciton-exciton scattering
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|a Excitons
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|a Landforms
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|a Laser excitation
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|a Laser induced
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|a Layered semiconductors
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|a Local heating
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|a Molybdenum compounds
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|a Momentum scattering
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|a Monolayers
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|a Non-monotonic dependence
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|a Polarization
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|a Power densities
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|a Scattering rates
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|a Spatial positions
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|a Sulfur compounds
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|a Cadiz, F.
|e author
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|a Gerl, S.
|e author
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|a Taniguchi, T.
|e author
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|a Watanabe, K.
|e author
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|t npj 2D Materials and Applications
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