Magneto-Optics of Exciton Rydberg States in a Monolayer Semiconductor, and Determination of Exciton Mass

ORAL

Abstract

Historically, optical spectroscopy in high magnetic fields has provided an especially powerful way to identify and quantify excited Rydberg excitons in semiconductors, because each Rydberg state shifts very differently with increasing field. Crucially, these shifts can directly reveal fundamental parameters such as the exciton's size, mass, and spin -- essential information for benchmarking theoretical models. Here we report 65 tesla magneto-absorption spectroscopy of exciton Rydberg states in the archetypal monolayer semiconductor WSe2 [1]. The strongly field-dependent and distinct energy shifts of the 2s, 3s, and 4s excited neutral excitons not only permits their unambiguous identification but also allows for quantitative comparison with leading theoretical models. Both the sizes (via low-field diamagnetic shifts) and the energies of the ns exciton states agree remarkably well with detailed numerical simulations using the non-hydrogenic screened Keldysh potential for 2D semiconductors. Moreover, at the highest magnetic fields the nearly-linear diamagnetic shifts of the weakly-bound 3s and 4s excitons provide a direct and unambiguous experimental measure of the exciton’s reduced mass, mr = 0.20±0.01 m0. [1] Stier et al., arXiv:1709.00123

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Presenters

  • Scott Crooker

    National High Magnetic Field Laboratory, Los Alamos National Laboratory, National High Magnetic Field Laboratory, Los Alamos National Lab, Los Alamos National Laboratory, NHMFL, Los Alamos National Laboratory

Authors

  • Scott Crooker

    National High Magnetic Field Laboratory, Los Alamos National Laboratory, National High Magnetic Field Laboratory, Los Alamos National Lab, Los Alamos National Laboratory, NHMFL, Los Alamos National Laboratory

  • Andreas Stier

    National High Magnetic Field Laboratory, Los Alamos National Lab

  • Nathan Wilson

    University of Washington, Department of Physics, University of Washington

  • Kirill Velizhanin

    Los Alamos National Laboratory, Theoretical Division, Los Alamos National Lab

  • Junichiro Kono

    Rice University, Department of Physics and Astronomy, Rice University

  • Xiaodong Xu

    University of Washington, Univ of Washington, Physics, Univ of Washington, Department of Physics, University of Washington, Physics, University of Washington, Physics, and Materials Science and Engineering, Univ of Washington, Department of Physics, University of Washington - Seattle