Probing Enhanced Electron-Phonon Coupling in Graphene by Infrared Resonance Raman Spectroscopy.

Physical review letters 2023 Jun 23

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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.

Citation

Tommaso Venanzi, Lorenzo Graziotto, Francesco Macheda, Simone Sotgiu, Taoufiq Ouaj, Elena Stellino, Claudia Fasolato, Paolo Postorino, Vaidotas Mišeikis, Marvin Metzelaars, Paul Kögerler, Bernd Beschoten, Camilla Coletti, Stefano Roddaro, Matteo Calandra, Michele Ortolani, Christoph Stampfer, Francesco Mauri, Leonetta Baldassarre. Probing Enhanced Electron-Phonon Coupling in Graphene by Infrared Resonance Raman Spectroscopy. Physical review letters. 2023 Jun 23;130(25):256901