Magnetoresistance of interleaved and separated Co/Cu multilayers in the CPP mode

We have measured the field dependence of the magnetoresistance MR(H) in the CPP mode for two types of magnetic multilayers that differ only in the ord ering of the magnetic layers: [Co (10 Angstrom)/Cu/Co (60 Angstrom)/Cu](N) and [Co (10 Angstrom)/Cu](N) [Co (60 Angstrom)/Cu](N), with the Cu layers a lways being 200 Angstrom. The series resistor model predicts that in the CP P mode, MR(H) is independent of the ordering of the layers. Nevertheless, t he MR(H) curves measured were found to be completely different for the two cases. We suggest that the reason for this difference is that the electron mean free path is long enough that the potential that scatters the electron s is due to pairs of neighboring magnetic layers, which differ for the two types of magnetic multilayers. (C) 2000 American Institute of Physics. [S00 21-8979(00)57408-8].