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A tunable phonon–exciton Fano system in bilayer graphene

Nature Nanotechnology volume 5, pages 32–36 (2010)Cite this article

Abstract

Fano resonances are features in absorption, scattering or transport spectra resulting from the interaction of discrete and continuum states. They have been observed in a variety of systems1,2,3,4,5,6. Here, we report a many-body Fano resonance in bilayer graphene that is continuously tunable by means of electrical gating. Discrete phonons and continuous exciton (electron–hole pair) transitions are coupled by electron–phonon interactions, yielding a new hybrid phonon–exciton excited state. It may also be possible to control the phonon–exciton coupling with an optical field. This tunable phonon–exciton system could allow novel applications such as phonon lasers.

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Figure 1: Dual-gate bilayer graphene as a tunable Fano system.
Figure 2: Infrared absorption spectra of the gate-tunable Fano resonance.
Figure 3: Fano parameters as a function of tunable bandgap in undoped bilayer graphene.

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Acknowledgements

This work was supported by the University of California at Berkeley and the Office of Basic Energy Sciences, US Department of Energy under contract no. DE-AC03-76SF0098 (Materials Science Division) and contract no. DE-AC02-05CH11231 (Advanced Light Source). Y.Z. and F.W. acknowledge support from a Miller Fellowship and a Sloan Fellowship, respectively. T.T.T. is partially supported by the National Science Council, Taiwan.

Author information

Author notes

  1. Yuanbo Zhang

    Present address: Present address: Department of Physics, Fudan University, Shanghai 200433, China (Y.Z.),

  2. Tsung-Ta Tang and Yuanbo Zhang: These authors contributed equally to this work

Authors and Affiliations

  1. Department of Physics, University of California at Berkeley, Berkeley, 94720, California, USA

    Tsung-Ta Tang, Yuanbo Zhang, Cheol-Hwan Park, Baisong Geng, Caglar Girit, Alex Zettl, Michael F. Crommie, Steven G. Louie, Y. Ron Shen & Feng Wang

  2. School of Physical Science and Technology, Lanzhou University, Lanzhou, 730000, China

    Baisong Geng

  3. Advanced Light Source Division, Lawrence Berkeley National Laboratory, Berkeley, 94720, California, USA

    Zhao Hao & Michael C. Martin

  4. Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, 94720, California, USA

    Alex Zettl, Michael F. Crommie, Steven G. Louie, Y. Ron Shen & Feng Wang

  5. Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, 94720, California, USA

    Zhao Hao

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Contributions

F.W. designed the experiment. T.T.T, Y.Z., B.G. and C.G. fabricated the sample. T.T.T., Y.Z., Z.H., M.C.M. and F.W. performed infrared spectroscopy measurements. C.H.P., S.G.L and F.W. carried out the calculations. T.T.T., Y.Z., C.H.P, A.Z., M.F.C., S.G.L, Y.R.S. and F.W. co-wrote the paper.

Corresponding author

Correspondence to Feng Wang.

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Tang, TT., Zhang, Y., Park, CH. et al. A tunable phonon–exciton Fano system in bilayer graphene. Nature Nanotech 5, 32–36 (2010). https://doi.org/10.1038/nnano.2009.334

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