Influence of a dielectric layer transparency on the overdamped Josephson junction dynamics

Abstract

Dynamical properties of the superconducting tunnel junctions with no impurities are investigated for the temperatures close to the critical temperature. A general case with no restrictions on the dielectric layer transparency is considered. As a result, the current states in Josephson junctions are described by the anharmonic current-phase relation, which differs significantly from the sinusoidal shape. The dependence of the junction resistance on the dielectric layer transparency is also taken into account. In the framework of the overdamped resistive model, the first-order differential equation for the time-dependent phase difference is derived and solved analytically. The period of the Josephson phase increment is shown to increase when the transparency of the layer is increased. The current–voltage characteristics of a Josephson junction are obtained. The average voltage drop decreases when the transparency increases. Finally, the influence of the thermal fluctuations on the phase dynamics is studied. The mean residence time of the junction in the superconducting state increases drastically when the layer transparency is decreased.