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, Tommaso; Graziotto, Lorenzo; Macheda, Francesco; Sotgiu, Simone; Ouaj, Taoufiq; Stellino, Elena; Fasolato, Claudia; Postorino, Paolo; Mišeikis, Vaidotas; Metzelaars, Marvin; Kögerler, Paul; Beschoten, Bernd; Coletti, Camilla; Roddaro, Stefano; Calandra, Matteo; Ortolani, Michele; Stampfer, Christoph; Mauri, Francesco; Baldassarre, Leonetta. - In: PHYSICAL REVIEW LETTERS. - ISSN 0031-9007. - 130:25(2023), p. 256901. [10.1103/PhysRevLett.130.256901]
Probing Enhanced Electron-Phonon Coupling in Graphene by Infrared Resonance Raman Spectroscopy
Calandra, Matteo;
2023-01-01
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.| File | Dimensione | Formato | |
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