Abstract
We have examined the dependence of the magnetism from perpendicular magnetic anisotropy with Co thickness in [Pt/Co] multilayers coupled to a NiO layer. We measure a perpendicular exchange bias field that changes polarity with Co thickness and find that with 2 nm of Co the perpendicular magnetic anisotropy is no longer present. Further evidence of the change in the Co layers preferred orientation is offered by zero field cooled susceptometry, where the low temperature susceptibility is negative for thin Co layers (0.9-1.2 nm) and becomes positive with increasing Co thickness (1.5-2.0 nm). Thin Co layered films also exhibit a compensation point around 100 K. These results indicate that the Co and NiO interface moments are coupled strongly and that there is competition between Pt/Co and Co/Ni at the film layer interfaces that sets the overall anisotropy from perpendicular and parallel configurations. © 2010 American Institute of Physics.