Trion valley coherence in monolayer transition metal dichalcogenides

ORAL

Abstract

Excitons and trions in monolayer transition metal dichalcogenides are formed at the boundary of the Brillouin zone at two inequivalent K and K’ valleys. Because of the valley contrasting optical selection rule, excitons and trions can be preferentially created using in a selected valley using light with a particular circular polariztion. Valley coherence — the coherent superposition between the excitonic states in the two valleys can be generated by a linearly polarized excitation. Exciton valley coherence has been detected as linearly polarized PL emission. However, the same method is not applicable to trions due to the spin-photon entanglement. With two-dimnensional Fourier transform spectroscopy, we explicitly measure the nonradiative exciton and trion valley coherence. Unlike exction, whose valley coherent time is limited by intrinsic fast population decay and electron-hole exchange interaction, our result shows that trion valley coherent time is limited by intra-valley pure dephasing processes.

*The work is supported by DOE DE-SC0012670, Welch F-1473, Welch F-1662, NSF EFMA-1542747, Humboldt fellowship, DFG GRK 1570 and DGE KO3612/1-1

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Presenters

  • Kai Hao

    • Department of Physics, Univerisity of Texas at Austin

Authors

  • Kai Hao

    • Department of Physics, Univerisity of Texas at Austin

  • Lixiang Xu

    • Department of Physics, Univerisity of Texas at Austin

  • Fengcheng Wu

    • Argonne National Laboratory
    • Department of Physics, Univerisity of Texas at Austin
    • Argonne National Lab

  • Philipp Nagler

    • Department of Physics, University of Regensburg

  • Kha Tran

    • Department of Physics, Univerisity of Texas at Austin
    • Department of Physics, Univ of Texas, Austin

  • Xin Ma

    • Department of Physics, Univerisity of Texas at Austin

  • Christian Schüller

    • Institut für Experimentelle und Angewandte Physik, Universität Regensburg
    • Department of Physics, University of Regensburg

  • Tobias Korn

    • Institut für Experimentelle und Angewandte Physik, Universität Regensburg
    • Department of Physics, University of Regensburg

  • Allan MacDonald

    • Physics department, University of Texas at Austin
    • Physics, University of Texas, Austin
    • Department of Physics, The University of Texas at Austin
    • Physics , Univ of Texas, Austin
    • Univ of Texas at Austin
    • Physics, The University of Texas at Austin
    • Department of Physics, Univerisity of Texas at Austin
    • The University of Texas at Austin
    • University of Texas

  • Galan Moody

    • National Institute of Standards & Technology

  • Xiaoqin (Elaine) Li

    • University of Texas at Austin
    • Department of Physics, Univerisity of Texas at Austin
    • Department of Physics, Univ of Texas, Austin
    • Univ of Texas, Austin