Regensburg 2010 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 50: Graphene and Carbon Nanotubes

HL 50.7: Vortrag

Donnerstag, 25. März 2010, 11:15–11:30, H15

Phase coherent transport in graphene nanoribbons — •Silvia Schmidmeier, Daniel Neumaier, Dieter Weiss, and Jonathan Eroms — Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Germany

Quantum interference effects result in quantum corrections of the conductivity. One of these corrections, which results from interference of electron waves that are scattered by disorder and form closed trajectories, cause a decrease of conductivity and is well-known as weak localization. Another correction of the conductivity is due to universal conductance fluctuations, which appear when the phase coherence length is comparable to the sample length.

Here we investigate electronic transport in graphene nanoribbons (GNR). The lateral confinement of the charge carriers in the quasi one-dimensional ribbons creates an energy gap near the charge neutrality point, where the gap depends on the width of the GNR. The GNRs were fabricated by electron beam lithography and plasma etching techniques. Widths of 50nm were achieved. We measured the magnetoconductance in a perpendicular magnetic field for different temperatures down to 20mK. These measurements allowed us to determine the phase coherence length both from weak localization as well as from the amplitude of the universal conductance fluctuations. At mK temperatures the phase coherence length exceeds the lateral dimensions of the GNR, indicating that etching does not destroy the phase coherent properties of the sample.