Oscillatory exchange coupling and giant magnetoresistance via Cu-X alloys (X=Au, Fe, Ni)

Abstract

Oscillatory interlayer coupling and giant magnetoresistance is reported in (111) textured polyciystalline multilayers composed of thin Co layers separated by spacer layers comprised of various Cu-based alloys. Substitution of Cu by elements with the same valence electron density as Cu, such as Au, has little effect on the oscillation period of ≃ 10 to 11Å observed in pure Cu. In comparison, the substitution of Cu with elements with smaller numbers of valence electrons such as Fe or Ni leads to substantially increased oscillation periods. The experimental dependence of the oscillation period on Ni concentration in Cu1-xNixalloys is found to be in good agreement with the theoretical dependence calculated from a simple linear interpolation of the paramagnetic Cu and Ni band structures. Quite remarkably the magnitude of the saturation magnetoresistance remains extremely large even for highly resistive Cu alloys. © 1993 IOP Pubilishing Ltd.