The dependence of the angular distribution of the magnetization in ultrathin epitaxial Co layers upon the thickness of Au and Cu overlayers is studied in situ by spin-polarized low-energy electron microscopy in the thickness range from 0 to 3 monolayers. Only Cu overlayers cause a peak in the coverage dependence of the perpendicular magnetic anisotropy at 1.5 ML coverage. The relation between the nanostructure of the overlayers and the anisotropy is discussed.

• Received 1 July 1998

DOI:https://doi.org/10.1103/PhysRevB.59.468