Abstract
As individual layers in [PtCo]4 NiO multilayers become thinner, the role of interfaces and surfaces can dominate that of the bulk. A perpendicular interface contribution to the magnetic anisotropy can rotate the easy magnetization direction from within the film plane to perpendicular to the film plane as the thickness of Co is below the critical value in the range of nano- or subnanoscale. In this work, the mixed CoPt phases were found to be responsible for the perpendicular magnetic anisotropy, driven by the negative heat of mixing and relatively unstable interfacial structure caused by the different structure of the NiO underlayer as the thickness of Co is below 1.2 nm. © 2008 The Electrochemical Society.