THEORY OF THE EXCHANGE COUPLING IN MAGNETIC METALLIC MULTILAYERS

Existing theories of the oscillatory exchange coupling in magnetic met allic multilayers are reconciled within a common approach. It is shown that Ruderman-Kittel-Kasuya-Yosida-type theories and full-confinement quantum-well results are obtained as limiting cases. Numerically usef ul and model-independent closed-form expressions for the exchange coup ling across a nonmagnetic spacer are obtained in terms of the one-elec tron propagators. The theory can be extended to deal with nonmagnetic alloy spacers and it is argued that the existence of disorder in the s pacer may lead to significant reduction of the interlayer coupling.