Length dependent properties of SNS microbridges

Using an in-situ, self-aligned deposition scheme, arrays of variable length SNS junctions in the range of 0.05μm to 1 μm have been fabricated. Arrays of SNS microbridges of lead-copper and niobium-copper fabricated using this technique have been used to study the length dependence, at constant temperature, of the critical current Icand bridge resistance Rd. For bridges with lengths L greater than the normal metal coherence length\xi_{n}(T), the dependence of Icon L is consistent with an exponential dependence on the reduced length\ell=L/\xi_{n}(T). For shorter bridges, deviations from this behavior is seen. It was also found that the bridge resistance Rddoes not vary linearly with the geometric bridge length but appears to approach a finite value asL \rightarrow 0.