Studies of tin Josephson junctions of anomalously high supercurrent

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Abstract
We have studied tin Josephson junctions that have unusually high supercurrents and which exhibit bulk values for superconducting energy gap and critical temperature. We find good agreement with the BCS theory for the temperature dependence of the energy gap and the maximum supercurrent. Our results agree with the prediction, based on strong-coupling theory, that the ratio of gap to critical temperature should be slightly higher than the BCS value. For the maximum supercurrent we find the BCS value in disagreement with the strong-coupling prediction that the supercurrent should not exceed 91% of the BCS value.