Imaging nanoscale photocurrent in the twisted bilayer graphene by magneto-scanning near-field optical microscopy

ORAL

Abstract

In graphene, one main mechanism for generating photocurrent is the thermoelectric effect. For the twisted bilayer graphene (TBG), photocurrent induced by optical thermoelectric effect has been used to probe the local superlattice structure and electronic structure in nanoscales1,2, while the effect of high magnetic field on nano-photocurrent has never been explored. Here in this talk, using the newly developed magneto-scanning near field optical microscopy (m-SNOM), we will show nano-photocurrent measurements in TBG samples under high magnetic field up to 7T and discuss these magneto-photocurrent phenomena in terms of thermal Nernst effect.

1. Sai S. Sunku, et al., Nano-photocurrent Mapping of Local Electronic Structure in Twisted Bilayer Graphene, Nano Lett. 20, 2958 (2020).

2. Niels C. H. Hesp, et al., Nano-imaging photoresponse in a moiré unit cell of minimally twisted bilayer graphene, Nature Commun. 12, 1640 (2021).

*M.K.L. acknowledges support from the NSF Faculty Early Career Development Program under Grant No. DMR - 2045425. Research on polaritons is supported as part of Programmable Quantum Materials, an Energy Frontier Research Center funded by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES), under award DE-SC0019443.

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Presenters

  • Zengyi Du

    • Brookhaven National Lab.
    • Stony Brook University

Authors

  • Zengyi Du

    • Brookhaven National Lab.
    • Stony Brook University

  • Makoto Tsuneto

    • Stony Brook University

  • Yinan Dong

    • Columbia University

  • Baichang Li

    • Columbia University

  • Zijian Zhou

    • Stony Brook University

  • Michael Dapolito

    • Columbia University

  • Wenjun Zheng

    • Stony Brook University

  • Lukas Wehmeier

    • Brookhaven National Laboratory

  • Xu Du

    • Stony Brook University (SUNY)
    • Stony Brook University

  • James C Hone

    • Columbia University

  • Dmitri N Basov

    • Columbia University
    • Department of Physics, Columbia University, New York, NY, USA

  • Mengkun Liu

    • Stony Brook University (SUNY)