Magnetic behavior of a superconductor-normal-conductor composite (SN)x

We describe the magnetic properties expected from a finely divided superconductor-normal-conductor composite. We show that this behavior matches that exhibited by samples of superconducting polysulfur nitride (SN)x. The implications of the composite model for critical-field measurements and for the observation of a decoupling transition are discussed. © 1981 The American Physical Society.