  We show that some metals and alloys (X = Cu, Ag, FeMn, or Cu and Ag combined
with each other), sputtered between ferromagnetic Co and superconducting Nb,
produce no change in current-perpendicular-to-plane magnetoresistance (CPP-MR)
in a carefully designed CPP-spin-valve. In contrast, other metals (Ru or Au) or
combinations (Cu or Ag combined with Au, Ru, or FeMn) change the CPP-MR, in
some cases even reversing its sign. We ascribe these changes to activation of
magnetic scattering anisotropies at a ferromagnetic/superconducting interface,
apparently by strong spin-flipping between the Co and Nb layers.
