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HL: Fachverband Halbleiterphysik
HL 90: Graphene: Transport incl. Spin Physics and Magnetic Fields II
HL 90.5: Talk
Thursday, March 29, 2012, 18:00–18:15, ER 270
Length dependence of the resistance in graphite: influence of ballistic transport — •Pablo Esquinazi1, Jose Barzola-Quiquia1, Srujana Dusari1, and Nicolas Garcia2 — 1Division of Superconductivity and Magnetism, Institut für Experimentelle Physik II, Universität Leipzig, Linnéstraße 5, D-04103 Leipzig, Germany — 2Laboratorio de Física de Sistemas Pequeños y Nanotecnología, Consejo Superior de Investigaciones Científicas, E-28006 Madrid, Spain
Using a linear array of voltage electrodes with a separation of several micrometers on a 20 nm thick and 30 µm long multigraphene sample we show that the measured resistance does not follow the usual length dependence according to Ohm’s law. The deviations can be quantitatively explained taking into account Sharvin-Knudsen formula for ballistic transport. This allows us to obtain without free parameters the mean free path of the carriers in the sample at different temperatures. In agreement with recently reported values obtained with a different experimental method, we obtain that the carrier mean free path is of the order of ∼ 2 µm with a mobility µ ∼ 107 cm2V−1s−1. The results indicate that the usual Ohm’s law is not adequate to calculate the absolute resistivity of mesoscopic graphite samples.