Supercurrents through SNS proximity-induced junctions

Critical current measurements by Courtois et al. [Phys, Rev. B 52, 1162 (1995)] on proximity-induced superconductivity in a narrow metallic wire are analyzed by a junction model of the author based on the Ginzburg-Landau theory. Good agreement is found if one assumes that the length of at least one of the many superconducting cells is larger than anticipated by a factor of approximately 2, At low temperatures the size of the superconducting region in the normal metal is confined by the length of the normal cell. As a consequence, the critical current saturates below a temperature at which the length of the normal cell becomes approximately three characteristic lengths of the coherent state in the normal metal.