Dresden 2014 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 65: Poster: Graphene (HL jointly with MA, O)

O 65.9: Poster

Mittwoch, 2. April 2014, 17:00–20:00, P1

Twisted graphene bilayers, folded via atomic force microscope — •Johannes C. Rode, Dmitri Smirnov, Christopher Belke, and Rolf J. Haug — Institut für Festkörperphysik, Leibniz Universität Hannover

Naturally occurring double-layer graphene consists of two hexagonal lattices in Bernal stacking. We investigate the folding of single-layer graphene via atomic force microscope (AFM) and the electronic properties of thusly created bilayers. The crystal lattices of these are twisted against each other which affects the interlayer coupling, giving rise to interesting electronic properties like a screening effect and reduced Fermi velocities at higher twist angles. Furthermore, the influence of a moiré-superlattice or twist induced van-Hove-singularities can be expected at lower twist angles. Our samples are obtained by micromechanical cleavage of natural graphite and placed on a silicon substrate with a top layer of silicon dioxide. The atomic force microscope then serves as a tool to mechanically manipulate the sample by programmed tip movements. We show AFM-induced folding of graphene on a µm-scale which can afterwards be contacted via e-beam lithography. Magnetotransport measurements over the folded areas show interesting signatures like multiple origins of landau fans in the charge carrier concentration.