Oscillatory interlayer exchange coupling in [Pt/Co]n/NiO/[Co/Pt]n multilayers with perpendicular anisotropy:: Dependence on NiO and Pt layer thicknesses -: art. no. 224423

Interlayer exchange coupling has been studied in a series of [Pt(t(Pt) Angstrom)/Co(4 Angstrom)](n)/NiO(t(NiO))/[Co(4 Angstrom)/Pt(t(Pt) Angstrom)](n) multilayers with perpendicular anisotropy. The coupling oscillates between antiferromagnetic and ferromagnetic as a function of t(NiO) with a period of similar to5 Angstrom, and the oscillatory behavior is related to the antiferromagnetic ordering of the NiO layer. This interlayer coupling between two Co/Pt multilayers is shown to occur domain by domain by magnetic force microscopy imaging. For the strongest antiferromagnetic coupling at t(NiO)=11 Angstrom, an oscillation with a period of similar to6 Angstrom is superposed onto the exponential decay of the coupling strength as a function of t(Pt). The exponential decay with t(Pt) is ascribed to the exponential decay of the coupling between the Co layers across the Pt layers in each Co/Pt multilayer, and the superposed oscillatory behavior can be attributed to multiple reflections of electron waves at the Co/Pt interfaces and their interference. A linear dependence of the antiferromagnetic coupling strength on 1/n, (where n is the number of repeats), is suggestive of a surface interaction for this interlayer coupling.