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Strong Auger scattering in Landau-quantized graphene investigated by infrared pump-probe experiments
- Source :
- High Magnetic Fields in Semiconductor Physics, 03.-08.08.2014, Panama City Beach, USA
- Publication Year :
- 2014
-
Abstract
- The non-equidistant Landau-level (LL) spectrum of graphene enables the investigation of the carrier dynamics of distinct LL transitions. We present pump-probe measurements on multilayer epitaxial graphene, complemented by microscopic modelling. The free-electron laser (FEL) FELBE served as radiation source at a wavelength of 16.5 µm, which corresponds to a photon energy of 75 meV. At a magnetic field of 4.2 T, the photon energy gets resonant with the energetically degenerate LL transitions LL-1 → LL0 and LL0 → LL1. Circularly polarized radiation allows one to address one of these transitions selectively. Besides a strong increase of the pump-probe signal at 4.2 T, we observe a complex set of pump-probe signals for all four combinations of pump and probe polarization. For contrarily polarized pump and probe radiation, one would expect negative pump-probe signals, as the initial state of the probed transition is populated (pump: σ+; probe: σ-) or the final state of the probe gets depopulated. Our measurements show the counterintuitive result of positive pump-probe signals for the case of σ+-polarized pump radiation. The experimental findings are well described by microscopic calculations based on the density matrix formalism, which helped to reveal the origin of this behavior.
- Subjects :
- relaxation dynamics
graphene
Physics::Optics
Landau quantization
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Journal :
- High Magnetic Fields in Semiconductor Physics, 03.-08.08.2014, Panama City Beach, USA
- Accession number :
- edsair.od......4577..e941e00de6c73745eeea561866845292