Effect of impurities on the Josephson current through SNS junctions

The effect of impurities on the steady-state Josephson current through a superconductor—normal metal—superconductor junction is analyzed. It is shown that, when ξ0≪l∼d (l denoting mean free path length and d denoting the thickness of the normal metal layer), impurities cause an appreciable decrease in the current and a change in the form of its dependence on the phase. The dependence of the critical current for weak-superconduction current on the thickness of the normal metal layer is found to be of the form jc∼j0e−d/ζ with ζ denoting the effective coherence length and defined as the reciprocal of ζ−1=2πT/ℏvo/+1/l.

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