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Intervalley excitonic hybridization, optical selection rules, and imperfect circular dichroism in monolayer hBN

ORAL

Abstract

We perform first-principles GW plus Bethe-Salpeter equation calculations to investigate the photophysics of monolayer hexagonal boron nitride (hBN), revealing excitons with novel k-space characteristics. The excitonic states forming the first and third peaks in its absorption spectrum are s-like, but those of the second peak is notably p-like, a first finding of strong co-occurrence of bright s-like and bright p-like states in an intrinsic 2D material. Moreover, even though the k-space wavefunction of these excitonic states are centered at the K- and K'-valleys like in monolayer transition metal dichalcogenides, the envelope functions of the basis excitons at one valley have significant extents to the basin of the other valley. As a consequence, the optical response of monolayer hBN exhibits a lack of circular dichroism, as well as a coupling that induces an intervalley mixing between s- and p-like states.

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Presenters

  • Fang Zhang

    University of Macau, University of California at Berkeley, Lawrence Berkeley National Laboratory , and Southern University of Science and Technology

Authors

  • Fang Zhang

    University of Macau, University of California at Berkeley, Lawrence Berkeley National Laboratory , and Southern University of Science and Technology

  • Chin Shen Ong

    University of California at Berkeley, and Lawrence Berkeley National Laboratory, University of California, Berkeley, Department of Physics and Astronomy, Uppsala University

  • Jiawei Ruan

    University of California at Berkeley, and Lawrence Berkeley National Laboratory

  • Meng Wu

    University of California at Berkeley, and Lawrence Berkeley National Laboratory, University of California, Berkeley

  • Xingqiang Shi

    Southern University of Science and Technology

  • Zikang Tang

    University of Macau

  • Steven G Louie

    University of California at Berkeley, and Lawrence Berkeley National Laboratory, Physics Department, UC Berkeley and Lawrence Berkeley National Lab, University of California Berkeley, University of California, Berkeley, University of California at Berkeley; Lawrence Berkeley National Laboratory, University of California at Berkeley and Lawrence Berkeley National Laboratory, UC berkeley, University of California at Berkeley and Lawrence Berkeley National Lab, UC Berkeley & Lawrence Berkeley National Laboratory