EXTERNAL MAGNETIC-FIELD AND SELF-FIELD EFFECTS IN STACKED LONG JOSEPHSON-JUNCTIONS

We have fabricated and tested samples consisting of two long stacked J osephson junctions with direct access to the intermediate electrode, w hose thickness is smaller than London penetration depth lambda(L). The electrodes are patterned so that the junctions can be independently b iased in the overlap geometry. We report the behaviour of the critical current of one junction as a function of an applied magnetic field (w hile the other junction is unbiased) and as a function of the bias cur rent along the McCumber curve in the other junction. We find strong si milarity in the two cases and compare the experimental results with nu merical simulation.