J. Appl. Phys. 111, 033709 (2012)

P. Esquinazi, J. Barzola-Quiquia, S. Dusari, and N. García

Abstract

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 ~ 10⁷ cm² V^-1 s^-1.
The results indicate that the usual Ohm’s law is not adequate to calculate the absolute resistivity of
mesoscopic graphite samples.