BIPERIODIC OSCILLATORY COUPLING AS A FUNCTION OF 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 inte rlayer 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 effec t originates from Bloch-wave interference in the Ni layer, the observe d periods must be, and indeed can be, related to extremal spanning vec tors of the spin-resolved Ni Fermi surface. The experiment touches on the selection criteria for spanning vectors of Ni that determine the p eriods of the oscillations.