Dresden 2011 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 1: TR: Graphene 1 (jointly with MA, HL, and DY)
TT 1.8: Vortrag
Montag, 14. März 2011, 12:45–13:00, HSZ 03
Relaxation dynamics of graphene in magnetic fields close to the Dirac point — •Martin Mittendorff1, Stephan Winnerl1, Paulina Plochocka2, Piotr Kossacki2, Harald Schneider1, Milan Orlita2, Marek Potemski2, Mike Sprinkle3, Claire Berger3, Walter A. de Heer3, and Manfred Helm1 — 1Institut für Ionenstrahlphysik und Materialforschung, Helmholtz-Zentrum Dresden Rossendorf, Germany — 2Grenoble High Magnetic Field Laboratory, France — 3Georgia Institute of Technology, Atlanta, USA
The relaxation dynamics in graphene is of key importance for understanding the basic material properties as well as for high-frequency electronic and opto-electronic device applications. In addition to single colour pump-probe experiments in the THz range (photon energy: 14-30 meV) without magnetic field, we performed experiments at a photon energy of 18 meV in magnetic fields up to 1.34 T. For photon energies larger than twice the Fermi energy (approx. 10 meV) positive pump-probe signals were observed while for smaller photon energies pump-induced absorption occurred due to carrier heating. Relaxation times were around 30 ps. At magnetic fields around 0.23 T the pump-probe signal increases by a factor of 2.5. At this field the splitting of the zeroth to first Landau level is resonant with the photon energy.