Oscillatory Interlayer Exchange Coupling and Its Temperature Dependence in [Pt/Co]\u3csub\u3e3\u3c/sub\u3e/NiO/[Co/Pt]\u3csub\u3e3\u3c/sub\u3e Multilayers with Perpendicular Anisotropy

摘要

Interlayer exchange coupling that oscillates between antiferromagnetic and ferromagnetic as a function of NiO thickness has been observed in [Pt(5 Å)/Co(4 Å)]3/NiO(tNiO Å)/[Co(4 Å)/Pt(5 Å)]3 multilayers with out-of-plane anisotropy. The period of oscillation corresponds to ~2 monolayers of NiO. This oscillatory behavior is possibly attributed to the antiferromagnetic ordering in NiO. The antiferromagnetic interlayer exchange coupling for the 11 Å 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.