Effect of a NiO capping layer on the temperature dependence of the interlayer coupling in Co/Pt multilayer with perpendicular anisotropy

The effect of an ultra thin NiO(11Å) capping layer on the temperature dependence of the interlayer coupling of a [Pt(26.5Å)/Co(4Å)]3 multilayer with perpendicular anisotropy has been investigated. In the presence of the NiO(11Å) capping layer, the interlayer coupling between the Co layers has been observed to demonstrate interesting temperature-dependent transitions. Only the antiferromagnetic (AF) interlayer coupling exists at T≥270K. With the decrease of temperature, the coexistence of ferromagnetic (FM) and antiferromagnetic interlayer coupling is observed in the temperature range of 220K≤T≤270K. When the temperature is lower than 220K, only the ferromagnetic interlayer coupling exists. The temperature-dependent polarization of the Pt layers can be one of the origins for the observed AF-to-FM transitions.