Josephson Currents through Junctions with Normal Metal Barriers

Abstract

The SNS-contact junction in the thick-barrier limit (ξ0/2d ≪1) at low temperature (T ≪Tc) is simulated by a step-wise one-dimensional off-diagonal potential, with different macroscopic phases for each of the superconductors, comprising the junction. The one-particle Green's functions are constructed by taking into account the boundary scattering effects at the superconductor-normal metal interfaces completely, and are used to calculate the zero-voltage barrier supercurrent. The supercurrent is shown to be a sectionally linear periodic function of relative phase between the superconductors, the amplitude of which is inversely proportional to the thickness (2d) of the normal barrier. The associated phase coupling energy is conjectured by making use of the close analogy of the diagrammatical structures of the barrier supercurrents of SNS junction to that of SIS junction.