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Electric Field Effect Tuning of Electron-Phonon Coupling in Graphene
Gate-modulated low-temperature Raman spectra reveal that the electric field
effect (EFE), pervasive in contemporary electronics, has marked impacts on long
wavelength optical phonons of graphene. The EFE in this two dimensional
honeycomb lattice of carbon atoms creates large density modulations of carriers
with linear dispersion (known as Dirac fermions). Our EFE Raman spectra display
the interactions of lattice vibrations with these unusual carriers. The changes
of phonon frequency and line-width demonstrate optically the particle-hole
symmetry about the charge-neutral Dirac-point. The linear dependence of the
phonon frequency on the EFE-modulated Fermi energy is explained as the
electron-phonon coupling of mass-less Dirac fermions.Comment: 4 pages, 4 figure
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