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.

*This research was supported by the Department of Energy under Contract No. DE-AC02-05CH11231 at LBNL, and by the Science and Technology Development Fund Grant No. FDCT/013/2017/AMJ and the Multi-Year Research Grant No. MYRG-2018-00142-IAPME at U of Macau.

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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