Oscillatory interlayer exchange coupling and its temperature dependence in [Pt/Co]3/NiO/[Co/Pt]3 multilayers with perpendicular anisotropy

Interlayer exchange coupling that oscillates between antiferromagnetic and ferromagnetic as a function of NiO thickness has been observed in [Pt(5 A)/Co(4 A)](3)/NiO(t(NiO) A)/[Co(4 A)/Pt(5 A)](3) multilayers with out-of-plane anisotropy. The period of oscillation corresponds to approximately 2 monolayers of NiO. This oscillatory behavior is possibly attributed to the antiferromagnetic ordering in NiO. The antiferromagnetic interlayer exchange coupling for the 11 A NiO layer shows an increase in coupling strength with increasing temperature, in agreement with the quantum interference model of Bruno for insulating spacer layers. A coexistence of exchange biasing and antiferromagnetic interlayer exchange coupling has been observed below T=250 K.