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