Nonmonotonic ferromagnetic thickness dependence of out-of-plane interlayer coupling between two Co/Pt multilayers across a 11 A NiO spacer

摘要

In [Pt(5 A)/Co(t_(Co) A)]_3/NiO(11 A)/[Co(t_(Co) A)/Pt(5 A)]_3 multilayers, the out-of-plane antiferromagnetic interlayer coupling between the Co/Pt multilayers can be tailored via varying the Co layer thickness t_(Co). The coupling strength increases with increase of t_(Co), but after reaching a maximum at t_(Co)=4.5 A, it decreases with further increase of t_(Co). At t_(Co) >6 A, no out-of-plane antiferromagnetic interlayer coupling has been observed. This nonmonotonic dependence on t_(Co) of the coupling strength can be attributed to variation of the out-of-plane effective magnetic anisotropy in Co/Pt multilayers with t_(Co).