Microwave surface impedance of proximity-coupled superconducting (Nb) /   spin-glass (CuMn) bilayers
  The surface impedance of Nb/CuMn (superconducting/spin-glass) bilayers has been measured at 10 GHz with the parallel plate resonator technique to obtain information about the exotic behavior of the order parameter in superconducting/magnetic proximity systems. The data strongly differs from the superconducting/normal-metal case, showing the magnetic nature of the CuMn layer, which acts as a weak ferromagnet. The results are described in the framework of two models for the electrodynamics of superconducting/ferromagnetic (S/M) bilayers characterized by a proximity-coupling length scale which is independent of temperature. 
L. V. Mercaldo, Steven M. Anlage (Univ. of Maryland) and L. Maritato   (Univ. of Salerno)