Double-barrier Josephson junctions: theory and experiment

New theoretical and experimental results on double-barrier SIS'IS Josephson junctions are presented (I is a tunnel barrier, S' is a thin film with critical temperature lower than that of S). The previously developed microscopic model for the stationary case, which describes the critical currents in Nb/Al/Nb junctions, is extended to the non-equilibrium regime of finite voltage. In particular, an intrinsic shunting resistance is estimated from I-V curves. We formulate the requirements for interface barriers in order to realize non-hysteretic SIS'IS junctions with high critical current density and I/sub c/R/sub N/ products. A comparison with single-barrier SIS junctions with high critical current density is carried out.