Dresden 2014 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 41: Graphene: Transport (HL jointly with MA, O, TT)
O 41.8: Vortrag
Mittwoch, 2. April 2014, 11:30–11:45, POT 051
Carrier dynamics in graphene under Landau quantization — •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 ultrafast dynamics of low-energetic Dirac electrons in graphene under Landau quantization [1]. In a joint experiment-theory study, we provide calculations based on the density matrix formalism [2] as well as measurements of the relaxation dynamics via differential transmission spectroscopy.
As a consequence of the linear dispersion at the Dirac points, graphene exhibits a non-equidistant Landau level spectrum which allows to address specific transitions by optical pumping. Exploiting this to selectively excite the energetically lowest Landau levels, we employ pump-probe spectroscopy to explore the carrier dynamics in this regime. A surprising sign reversal in differential transmission spectra is observed both in experiment and theory and provides evidence for strong Auger scattering on a picosecond timescale. Our calculations even predict the occurrence of a substantial carrier multiplication in Landau quantized graphene [3].
[1] M. Mittendorff et al., (in preparation).
[2] E. Malic, A. Knorr, Graphene and Carbon Nanotubes: Ultrafast Optics and Relaxation Dynamics, (Wiley-VCH, Berlin, 2013).
[3] F. Wendler, A. Knorr, and E. Malic, (submitted).