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HL: Fachverband Halbleiterphysik

HL 81: Graphene: Transport

HL 81.8: Vortrag

Donnerstag, 17. März 2011, 16:30–16:45, POT 151

Investigating Aharonov-Bohm oscillations in a monolayer graphene ring structure — •Dmitri Smirnov, Hennrik Schmidt, and Rolf J. Haug — Institut für Festkörperphysik, Leibniz Universität Hannover, D-30167 Hannover, Germany

We analyse the electronical properties of a monolayer graphene ring. Graphene is obtained by micromechanical cleavage of natural graphite and is placed on a silicon substrate with a 285nm thick silicon dioxide. Monolayer graphene is found and identified via the optical microscope. The ring is formed using plasma etching and has an average radius of 280nm. After that the sample is contacted using standard electron beam lithography. Magnetotransport measurements are performed in a He3 cryostat with a base temperature of 0.5 Kelvin by varying the magnetic field up to 13 Tesla and the charge carrier concentration using an applied back gate voltage. Shubnikov-de-Haas oscillations and Quantum-Hall measurements through the ring show characteristic properties of monolayer graphene. We also observe Aharonov-Bohm oscillations for various charge carrier concentrations for both electron and holes with a period in magnetic field that fits the size of the ring.