Effects of impurities on the exchange coupling in magnetic metallic multilayers

In this work the variation of the exchange coupling between magnetic layers across a non-magnetic spacer layer, due to impurities of the magnetic mate rial in the spacer, is calculated. The impurities are treated in the dilute limit and beyond it. It is shown that the change per impurity is comparabl e to the unperturbed coupling per atom, and that it oscillates as a functio n of spacer layer thickness with the same period as that coupling, though w ith a different phase. The most favourable magnetic moment orientation of t he impurity is found for some spacer layer thicknesses and impurity positio ns. It is also shown that the short-period oscillations of the coupling may be much more affected by the presence of impurities than the long-period o nes.