Granular superconductors and ferromagnets: a proximity-effect-based analogue

We present a model and a set of measurements which demonstrate an analogy b etween superconducting and ferromagnetic granular films. For granular films of either Pb or Ni we are able to deposit sequential layers of different m aterial and measure transport and magnetoresistance measurements in situ. I n both cases, individual isolated grains are coupled via an overlayer mater ial which does not possess superconductivity or ferromagnetism of the under lying granular material. This coupling induces long-range order. We compare the two effects and discuss the similarities in terms of proximity effects .