SUPERCONDUCTIVITY AND MAGNETISM AT THE NANO-SCALE
Research on Superconductivity at the nano-scale started well before the term "nano" became fashionable. In early contributions dark field microscopy was used and allowed for the first to measure grain sizes and grain size distributions down to the nano-scale in films of granular Aluminum that comprised many layers of grains. Recently research on granular superconductivity is receiving increased attention because of its enhancement in the vicinity to a metal-insulator transition, predicted high temperature superconductivity in small clusters and a possible competition with magnetism. These new developments will be reviewed.