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Open Access Nano Express

Transport through a strongly coupled graphene quantum dot in perpendicular magnetic field

Johannes Güttinger1*, Christoph Stampfer12, Tobias Frey1, Thomas Ihn1 and Klaus Ensslin1

Author Affiliations

1 Solid State Physics Laboratory, ETH Zurich, 8093 Zurich, Switzerland

2 Current Address: JARA-FIT and II, Institute of Physics, RWTH Aachen, 52074 Aachen, Germany

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Nanoscale Research Letters 2011, 6:253  doi:10.1186/1556-276X-6-253

Published: 24 March 2011

Abstract

We present transport measurements on a strongly coupled graphene quantum dot in a perpendicular magnetic field. The device consists of an etched single-layer graphene flake with two narrow constrictions separating a 140 nm diameter island from source and drain graphene contacts. Lateral graphene gates are used to electrostatically tune the device. Measurements of Coulomb resonances, including constriction resonances and Coulomb diamonds prove the functionality of the graphene quantum dot with a charging energy of approximately 4.5 meV. We show the evolution of Coulomb resonances as a function of perpendicular magnetic field, which provides indications of the formation of the graphene specific 0th Landau level. Finally, we demonstrate that the complex pattern superimposing the quantum dot energy spectra is due to the formation of additional localized states with increasing magnetic field.