Biperiodic oscillatory coupling with the thickness of an embedded Ni layer in Co/Cu/Co/Ni/Co (100) and selection rules for the periods

A biperiodic oscillation of the strength of the antiferromagnetic interlayer coupling as a function of the thickness of an embedded Ni layer has been observed in an epitaxial Cu(100)/Co/Cu/Co/Ni/Co sample with the Cu interlayer and the Ni layer in the form of wedges. As the effect originates from Bloch-wave interference in the Ni layer, the observed periods must be, and indeed can be, related to extremal spanning vectors of the spin-resolved Ni Fermi surface. The experiment touches on the selection criteria for spanning vectors of Ni that determine the periods of the oscillations.