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HL: Fachverband Halbleiterphysik
HL 43: 2D semiconductors and van der Waals heterostructures V (joint session HL/DS/O)
HL 43.3: Vortrag
Mittwoch, 18. März 2020, 10:00–10:15, POT 81
Magneto-Raman Spectroscopy for Probing Electron-Phonon and Electron-Electron Interactions in Graphene — •Jens Sonntag1,2, Sven Reichardt1,3, Ludger Wirtz3, Mikhail Katsnelson4, Bernd Beschoten1, and Christoph Stampfer1,2 — 1JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Germany — 2Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, Germany — 3Physics and Materials Science Research Unit, University of Luxembourg, Luxembourg — 4Radboud University, Institute for Molecules and Materials, Nijmegen, Netherlands
We present charge carrier density-dependent magneto-Raman spectroscopy measurements on suspended graphene and hBN/graphene heterostructures to investigate electron-phonon and electron-electron interactions, both without applied magnetic field and within the quantum Hall regime.
Strikingly, at B=0 T we do not observe the expected strong renormalization of the G-mode energy as a function of charge carrier density n. We identify Laser induced heating and a limited electron-hole lifetime as possible origins.
Utilizing gate-tunable magneto-phonon resonances, we extract the charge carrier density-dependence of the Landau level transition energies and the associated effective Fermi velocity vF.
In contrast to the logarithmic divergence of vF at zero magnetic field, we find a piecewise linear scaling of vF as a function of n, due to a magnetic field-induced suppression of the long-range Coulomb interaction. Furthermore, we can estimate the excitonic correction to the energies of the Landau level transistions to ≈6 meV.