Berlin 2015 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 12: Graphene: THz, NIR, and Transport Properties (jointly with HL, O)
TT 12.5: Talk
Monday, March 16, 2015, 10:30–10:45, ER 270
Carrier dynamics in Landau-quantized graphene — •Florian Wendler1, Martin Mittendorff2, Stephan Winnerl2, Manfred Helm2, Andreas Knorr1, and Ermin Malic1 — 1Institut für Theoretische Physik, Nichtlineare Optik und Quantenelektronik, Technische Universität Berlin, Germany — 2Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany
We investigate the carrier dynamics in Landau-quantized graphene after an optical excitation using microscopic time-resolved calculations as well as differential transmission measurements. The calculations are performed within the density matrix theory accounting for the carrier-light, carrier-carrier, and carrier-phonon interaction which allows for a microscopic explanation of the experimental spectra.
The energy spectrum of Landau-quantized graphene is characterized by non-equidistant Landau levels where the optical selection rules enable a selective excitation of specific transitions. This is exploited to investigate the carrier dynamics in the energetically lowest Landau levels where an unexpected sign reversal in pump-probe spectra, observed in experiment and theory, provides an evidence for strong Auger scattering [1]. Based on our calculations we predict a substantial carrier multiplication [2]. Furthermore, the theory reveals the occurrence of population inversion in Landau-quantized graphene, suggesting its application as gain medium for a widely tunable Landau level laser[3].
[1] M. Mittendorff et al., Nat. Phys., DOI:10.1038/nphys3164.
[2] F. Wendler et al., Nat. Commun. 5:3703 (2014).
[3] F. Wendler, and E. Malic, arXiv:1410.2080v1.