Coherent current states in a two-band superconductor

Abstract

Homogeneous current states in thin films and Josephson current in superconducting microbridges are studied within the frame of a two-band Ginzburg-Landau theory. By solving the coupled system of equations for two order parameters the depairing current curves and Josephson current-phase relation are calculated for different values of phenomenological parameters gamma and eta. Coefficients gamma and eta describe the coupling of order parameters (proximity effect) and their gradients (drag effect) respectively. For definite values of parameters the dependence of current j on superfluid momentum contains local minimum and corresponding bi-stable states. It is shown that the Josephson microbridge from two-band superconductor can demonstrate pi-junction behaviour.