  We have carried out measurements of the magnetoresistance MR(H) in the CPP
(Current Perpendicular to the Plane) mode for two types of magnetic multilayers
which have different layer ordering. The series resistor model predicts that
CPP MR(H) is independent of the ordering of the layers. Nevertheless, the
measured MR(H) curves were found to be completely different for the following
two configurations:[Co(1nm)/Cu(20nm)/Co(6nm)/Cu(20nm)]*N and
[Co(1nm)/Cu(20nm)]*N[Co(6nm)/Cu(20nm)]*N showing that the above model is
incorrect. We have carried out a calculation showing that these results can be
explained quantitatively in terms of the non-local character of the electron
scattering, without the need to invoke spin-flip scattering or a short spin
diffusion length.
