Manipulation of room-temperature valley-coherent exciton-polaritons in atomically thin crystals by real and artificial magnetic fields
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Strong spin-orbit coupling and inversion symmetry breaking in transition metal dichalcogenide monolayers yield the intriguing effects of valley-dependent optical selection rules. As such, it is possible to substantially polarize valley excitons with chiral light and furthermore create coherent superpositions of K and K’ polarized states. Yet, at ambient conditions dephasing usually becomes too dominant, and valley coherence typically is not observable. Here, we demonstrate that valley coherence is, however, clearly observable for a single monolayer of WSe2, if it is strongly coupled to the optical mode of a high quality factor microcavity. The azimuthal vector, representing the phase of the valley coherent superposition, can be directly manipulated by applying magnetic fields, and furthermore, it sensibly reacts to the polarization anisotropy of the cavity which represents an artificial magnetic field. Our results are in qualitative and quantitative agreement with our model based on pseudospin rate equations, accounting for both effects of real and pseudo-magnetic fields.
Rupprecht , C , Sedov , E , Klaas , M , Knopf , H , Blei , M , Lundt , N , Tongay , S , Tanigunchi , T , Watanbe , K , Schulz , U , Kavokin , A , Eilenberger , F , Höfling , S & Schneider , C 2020 , ' Manipulation of room-temperature valley-coherent exciton-polaritons in atomically thin crystals by real and artificial magnetic fields ' , 2D Materials , vol. 7 , no. 3 , 035025 . https://doi.org/10.1088/2053-1583/ab8e90
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DescriptionThe Würzburg group acknowledges support by the state of Bavaria. C.S. acknowledges support by the European Research Commission (Project unLiMIt-2D). This work has been supported by the Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. F.E gratefully acknowledge the financial support by the German Federal Ministry of Education and Research via the funding “2D Nanomaterialien für die Nanoskopie der Zukunft”. Work of E.S. and A.K. was supported by foundation of Westlake University (Project No. 041020100118 ). E.S. acknowledges partial support from the Grant of the President of the Russian Federation for state support of young Russian scientists No. MK-2839.2019.2. A.K. acknowledges the Saint-Petersburg State University for the research grant ID 40847559. SK.W and T.T. acknowledge support from the Elemental Strategy Initiative conducted by the MEXT, Japan and the CREST (JPMJCR15F3), JST. S.T. acknowledges support by the NSF (DMR-1955668 and DMR-1838443). H.K. is supported via the Max Planck School of Photonics.
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