Josephson critical current in a long mesoscopic S-N-S junction - art. no. 064502

We carry out an extensive experimental and theoretical study of the Josephs on effect in S-N-S junctions made of a diffusive normal metal (N) embedded between two superconducting electrodes (S). Our experiments are performed o n Nb-Cu-Nb junctions with highly transparent interfaces. We give the predic tions of the quasiclassical theory in various regimes on a precise and quan titative level. We describe the crossover between the short- and the long-j unction regimes and provide the temperature dependence of the critical curr ent using dimensionless units CRNIc/epsilon (c) and k(B)T/epsilon (c), wher e epsilon (c) is the Thouless energy. Experimental and theoretical results are in excellent quantitative agreement.