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.
Probing enhanced electron-phonon coupling in graphene by infrared resonance Raman spectroscopy / Venanzi, T.; Graziotto, L.; Macheda, F.; Sotgiu, S.; Ouaj, T.; Stellino, E.; Fasolato, C.; Postorino, P.; Miseikis, V.; Metzelaars, M.; Kogerler, P.; Beschoten, B.; Coletti, C.; Roddaro, S.; Calandra, M.; Ortolani, M.; Stampfer, C.; Mauri, F.; Baldassarre, L.. - In: PHYSICAL REVIEW LETTERS. - ISSN 1079-7114. - 130:25(2023), pp. 1-6. [10.1103/PhysRevLett.130.256901]
Probing enhanced electron-phonon coupling in graphene by infrared resonance Raman spectroscopy
Macheda F.;Ortolani M.;
2023
Abstract
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.
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