Using polarized neutron reflectometry (PNR) and high angle neutron scattering from Fe/Cr(001) superlattices, we demonstrate how the non-collinear exchange coupling between the Fe layers is caused by a frustration between antiferromagnetic Cr domains. This induces a spiral modulation of the Cr not observed in bulk. PNR and magnetization measurements show that the noncollinear coupling vanishes above the Néel temperature of this commensurate Cr order. The results are consistent with a recent model for non-collinear exchange coupling over antiferromagnetic interlayers.

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We have studied the non-collinear interlayer exchange coupling in Fe/Cr(001) superlattices as a function of growth temperature using polarized neutron reflectometry with exit beam polarization analysis. We confirm that the occurrence of non-collinear spin structures is correlated with long-range lateral Cr thickness fluctuations, which, in turn, depend on the growth temperature. We find surprisingly strong coupling between the Fe layers. We explain our data using the recently proposed proximity magnetism model instead of the currently used theory of bilinear and biquadratic exchange coupling.

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We have studied the anisotropy behavior of antiferromagnetically (AFM) coupled fcc Co/Cu(001) sandwiches and superlattices. Magneto-optical Kerr effect measurements on samples with Cu film thicknesses in the range of the second antiferromagnetic maximum reveal characteristic shapes of the hysteresis loops in close agreement with theoretical predictions. For the AFM coupled samples we infer antiparallel spin orientations in remanence perpendicular to the originally applied magnetic field direction. Changing the magnetic layer thickness and maintaining a constant thickness of the spacer completely alters the shape of the hysteresis loops. The loops of weakly coupled AFM layers show characteristic steps, indicative for a rather unusual nonsymmetric spin state. This behavior can be explained by the competing effects of anisotropy with the exchange coupling.