Dresden 2017 – scientific programme
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O: Fachverband Oberflächenphysik
O 94: Graphene: Electronic Properties, Structure and Substrate Interaction II
O 94.6: Talk
Thursday, March 23, 2017, 16:15–16:30, TRE Ma
Strong electron-phonon coupling in the σ band of graphene — Federico Mazzola1, Thomas Frederiksen2, Thiagarajan Balasubramanian3, Philip Hofmann4, •Bo Hellsing5, and Justin W. Wells1 — 1Department of Physics, Norwegian University of Science and Technology (NTNU), Trondheim, Norway — 2Donostia International Physics Center (DIPC) – UPV/EHU, San Sebastián, Spain — 3MAX IV Laboratory, Lund, Sweden — 4Department of Physics, Aarhus University, Denmark — 5Department of Physics, University of Gothenburg, Sweden
First-principles studies of the electron-phonon coupling in graphene predict a high coupling strength for the σ band with values of the dimensionless mass-enhancement parameter λ up to 0.9. Near the top of the σ band λ is found to be ≈ 0.7. This value is consistent with the observed kink in the σ band dispersion near the Γ-point in the Brillion zone. The calculations show that the electron-phonon coupling is driven primarily by the optical LO and TO phonon modes in graphene. The photoemission intensity from the σ band is strongly suppressed near the Γ-point due to sublattice interference effects. These effects are removed by taking data in the neighbouring Brioullin zone. By this we have been able to disentangle the influence of sublattice interference and electron-phonon coupling. A rigorous analysis of the experimentally determined complex self-energy further supports the assignment of the observed kink to strong electron-phonon coupling and yields λ ≈ 0.6, in excellent agreement with the calculations.