Berlin 2012 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 78: Transport: Graphene 1 (jointly with TT, MA, DY, DS, O)

HL 78.7: Talk

Thursday, March 29, 2012, 11:00–11:15, BH 334

Manifestation of electron-electron interaction in the magnetoresistance of graphene — •Johannes Jobst¹, Daniel Waldmann¹, Igor V. Gornyi^2,3, Alexander D. Mirlin^2,4,5, and Heiko B. Weber¹ — ¹Lehrstuhl für Angewandte Physik, Universität Erlangen-Nürnberg, Erlangen, Germany — ²Institut für Nanotechnologie, Karlsruhe Institute of Technology, Karlsruhe, Germany — ³A.F. Ioffe Physico-Technical Institute, St. Petersburg, Russia — ⁴Inst. für Theorie der kondensierten Materie, Karlsruhe Institute of Technology, Karlsruhe, Germany — ⁵Petersburg Nuclear Physics Institute, St. Petersburg, Russia

We investigate the magnetotransport in large area graphene Hall bars epitaxially grown on silicon carbide. In the intermediate field regime between weak localization and Landau quantization the observed temperature-dependent parabolic magnetoresistivity is a manifestation of electron-electron interaction. We can consistently describe the data with a model for diffusive (magneto)transport that covers the crossover to the ballistic regime. We find a temperature-driven crossover related to the reduction of the multiplet modes contributing to electron-electron interaction from 7 to 3 due to intervalley scattering. In addition we find a field-driven crossover from purely diffusive to partially ballistic behavior.