Josephson effect in nanographite films

Abstract

In nanographite films, for the first time the Josephson current at room temperature has been obtained when measuring the current-voltage characteristics. Sach measurement confirms the earlier observations in nanographite film the effects of weak superconductivity: zeroing of the temperature dependence at 650 K of constant voltage on the sample when it exposed to an alternating microwave voltage due to the inverse Josephson effect, as well as the observation of local areas with the structure of magnetic vortices in a magnetic force microscope at room temperature. The resulting critical current value of 0.8 μA is significantly lower than expected values for the superconducting gap, as well as for pinning at the Bean--Levingston barrier. The measures for increasing the critical current is proposed. Keywords: Josephson effect, nanographite film, superconductivity, room temperature.