Resonant Excitation of Graphene K-Phonon and Intra Landau-Level Excitons in Magneto-Optical Spectroscopy

Milan Orlita (1) , Liang Z. Tan (2, 3) , Marek Potemski (1) , Michael Sprinkle (4) , Claire Berger (5) , Walt. A. de Heer (4) , Steven G. Louie (2, 3) , Gines Martinez Garcia (1)

1 LNCMI-G - Laboratoire national des champs magnétiques intenses - Grenoble
2 Department of Physics [Berkeley]
3 Materials Science Division [LBNL Berkeley]
4 School of Physics
5 NEEL - QuantECA - Circuits électroniques quantiques Alpes

Precise infrared magnetotransmission experiments have been performed in magnetic fields up to 32 T on a series of multilayer epitaxial graphene samples. We observe changes in the spectral features and broadening of the main cyclotron transition when the incoming photon energy is in resonance with the lowest Landau level separation and the energy of a K point optical phonon. We have developed a theory that explains and quantitatively reproduces the frequency and magnetic field dependence of the phenomenon as the absorption of a photon together with the simultaneous creation of an intervalley, intra-Landau-level exciton, and a K phonon.

Domaines: Systèmes mésoscopiques et effet Hall quantique [cond-mat.mes-hall]

Milan Orlita, Liang Z. Tan, Marek Potemski, Michael Sprinkle, Claire Berger, et al.. Resonant Excitation of Graphene K-Phonon and Intra Landau-Level Excitons in Magneto-Optical Spectroscopy. Physical Review Letters, 2012, 108 (24), pp.247401. ⟨10.1103/PhysRevLett.108.247401⟩. ⟨hal-01002910⟩