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 \textit{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.
@article{arxiv.2212.01342,
title = {Probing enhanced electron-phonon coupling in graphene by infrared resonance Raman spectroscopy},
author = {Tommaso Venanzi and Lorenzo Graziotto and Francesco Macheda and Simone Sotgiu and Taoufiq Ouaj and Elena Stellino and Claudia Fasolato and Paolo Postorino and Vaidotas Mišeikis and Marvin Metzelaars and Paul Kögerler and Bernd Beschoten and Camilla Coletti and Stefano Roddaro and Matteo Calandra and Michele Ortolani and Christoph Stampfer and Francesco Mauri and Leonetta Baldassarre},
journal= {arXiv preprint arXiv:2212.01342},
year = {2025}
}