Resistance of clean SNS sandwiches

Measurements are reported of the resistance of In/W/In sandwiches. The data close to T c are found to fit the theory developed by Battersby and Waldram (1984). In an attempt to explain further the data below T c new expressions for the excitation reflection and transmission coefficients at the interface have been developed, by matching solutions to the Bogoliubov equations at the interface in two simple models. These models give poor fits to the data at temperatures below about 0.6 T c , where the theoretical curve is found to have the wrong curvature. This discrepancy has been resolved by allowing for the penetration of the energy gap of the In into the W.