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News 23.04.2024
New publication: Negative electronic compressibility in charge islands in twisted bilayer graphene
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News 22.06.2023
New publication: Probing Enhanced Electron-Phonon Coupling in Graphene by Infrared Resonance Raman Spectroscopy
Phys. Rev. Lett. 130, 256901 (2023) We report on resonance Raman spectroscopy measurements with excitation photon energy down to 1.16 eV on graphene, to study how low-energy carriers interact with lattice vibrations. Thanks to the excitation energy close to the Dirac point at K, we unveil a giant increase of the intensity ratio between the double-resonant 2D and 2D′ peaks with respect to that measured in graphite. Comparing with fully ab initio theoretical calculations, we conclude that the observation is explained by an enhanced, momentum-dependent coupling between electrons and Brillouin zone-boundary optical phonons. This finding applies to two-dimensional Dirac systems and has important consequences for the modeling of transport in graphene devices operating at room temperature.