Strong correlation effects in SNS junctions and failed superconductors

A wide variety of well characterized experimental systems exhibit anomalous metallic states in which current is carried by large superconducting quantum fluctuations that remain uncondensed to the lowest accessible temperatures. As a first step toward a theory of such a state, we revisit the case of a single SNS junction, but taking into account interaction effects in the normal metal portion of the junction. In particular, we identify circumstances in which magnetic fluctuations lead to dynamical variations in the sign of the Josephson coupling - i.e. in the sign of the local superfluid density. This has important implications for the theory of the anomalous metal more generally.