ANTIFERROMAGNETIC BIAS IN THE INTERLAYER MAGNETIC COUPLING

The interlayer coupling for thin spacer layers is predominantly antiferromagnetic in some metallic multilayered structures. We interpret this tendeney towards antiferromagnetism to arise from a competition between RKKY-like and superexchange contributions to the coupling. For a free-electron gas with no structure in the density of states above the Fermi level there is a complete cancellation of these contributions, so that coupling derived from the s-d model is indistinguishable from a point contact spin-dependent scattering potential. However, in real solids the non-cancellation of the non-oscillatory parts of these two contributions, i.e. antiferromagnetic bias, can arise from the structure of the density of states of the spacer layer close to the Fermi surface.