Observation of internal interfaces inPtxCo1−x(x≈0.7) alloy films: A likely cause of perpendicular magnetic anisotropy

X-ray-absorption measurements of the local structure about Pt and Co in thin polycrystalline ${\mathrm{Pt}}_{0.72}$ ${\mathrm{Co}}_{0.28}$ alloy films, which exhibit perpendicular magnetic anisotropy, indicate that the gross structure is fcc. However, the data reveal a directional anisotropy in the number of Co-Co bonds with an excess of Co-Co bonds in the film plane, consistent with two-dimensional clustering of Co. The resulting internal interfaces are analogous to those in Co/Pt multilayers suggesting a similar mechanism for the perpendicular magnetic anisotropy in these alloys.