Gate-tunable nanoplasmonic effects in single- and bi-layer graphene

ORAL

Abstract

We employed near-field infrared (IR) nanoscopy and nanoimaging to study mid-IR nanoplasmonic effects of both single-layer graphene (SLG) and bilayer graphene (BLG) on SiO2/Si substrate. In our previous study, we found that SLG enhanced and blueshifted the surface phonon resonance of SiO2 due to plasmon-phonon coupling [Z. Fei et al. Nano. Lett. 2011]. Here we report that both these effects are also observed in BLG. Using back-gate we were able to systematically change the carrier density in both SLG and BLG while monitoring the evolution of the hybrid plasmon-phonon resonance. New data are in accord with our point-dipole modeling results. IR imaging with nanoscale resolution revealed fringe patterns extending along the edges of both SLG and BLG. We ascribe these patterns to the interference of plasmon waves launched by the near-field probe with those reflected from the edges. Detailed analysis allowed us to observe gate-induced changes in the plasmon dispersion of both SLG and BLG, which are consistent with the notion of massless Dirac fermions in SLG and massive carriers in BLG.

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Authors

  • Zhe Fei

    • University of California, San Diego

  • Gregory Andreev

    • University of California, San Diego

  • Wenzhong Bao

    • University of California, Riverside

  • Aleksandr Rodin

    • UCSD
    • University of California, San Diego

  • Alexander McLeod

    • University of California, San Diego

  • Lingfeng Zhang

    • Boston University

  • Zeng Zhao

    • University of California, Riverside

  • Gerardo Dominguez

    • University of California, San Diego

  • Mark Thiemens

    • University of California, San Diego

  • Michael Fogler

    • University of California, San Diego

  • Antonio Castro-Neto

    • National University of Singapore

  • Chunning Lau

    • University of California, Riverside

  • Fritz Keilmann

    • Max Plank Institute of Quantum Optics

  • Dmitri Basov

    • UCSD
    • University of California, San Diego
    • University of California San Diego
    • Department of Physics, University of California, San Diego