CRITICAL CURRENT OF A JOSEPHSON-JUNCTION IN LAYERED SUPERCONDUCTORS

We present a microscopic theory for the temperature dependence of the critical Josephson current density j(c)(T) flowing through an insulati ng barrier situated between two layered superconductors. Our theory is quite general and allows us to address the question of the dependence of j(c)(T) on the bandwidth for electronic motion along the direction perpendicular to the barrier. In the limit in which k(B)T(c) is much smaller than this quantity the standard relationship due to Ambegaokar and Baratoff is recovered. In the opposite limit, however, the critic al current is substantially modified. We show in particular that in th is case j(c)(T) is generally quenched. The significance of our results as well as their relevance with respect to the experimental situation in the high-T(c) cuprates is discussed.