Determination of the current density distribution in Josephson tunnel junctions

The magnetic field dependence of the maximum Josephson current Im(Hy) in tunnel junctions is a function of the integral of the Josephson current density distribution in the direction of the magnetic field: j1(x)=j1(x, y) dy. It is shown that a determination of j1(x) from Im(H) is often ambiguous. Cases of different j1(x) with the same Im(H) are given. Experimental results of a study of the growth of microshorts in Josephson junctions are presented. Experimental configurations with which j1(x) can be determined are discussed. © 1975 The American Physical Society.