Dresden 2011 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 85: Poster Session II

HL 85.43: Poster

Thursday, March 17, 2011, 18:00–21:00, P4

Transport Measurements on Bilayer Graphene Systems — •Alexander W. Heine, Hennrik Schmidt, Patrick Barthold, Thomas Lüdtke, and Rolf J. Haug — Institut für Festkörperphysik, Leibniz Universität Hannover, D-30167 Hannover, Germany

We analyse electronic transport properties of coupled bilayer graphene sheets. Similar to monolayer graphene, bilayer graphene samples show a strong field effect but exhibit a different Berry’s phase in Shubnikov-de Haas oscillations. Our samples are prepared by micromechanical exfoliation and placed on top of a silicon wafer with a 330 nm thick layer of silicon dioxide. After that they are contacted using electron beam lithography and structured by plasma etching. Low temperature measurements were performed at temperatures down to 1.5 K in a liquid helium cryostat. The conductivity of the samples shows a strong dependence to an applied backgate voltage. By applying a magnetic field up to 13 T we observed Shubnikov-de Haas oscillations. As expected, the bilayer samples show a Berry’s phase different to the one of monolayer graphene. In the vertical resistance plateaus according to the minima of the oscillations are observed with a double step around filling factor zero which is typical for graphene bilayer systems.