  Utilizing spin-polarized scanning tunneling microscopy and spectroscopy, we
found coexistence of perpendicularly and in-plane magnetized cobalt nanoscale
islands on the Ag(111) surface, and the relationship between the moire
corrugation amplitude and the magnetization direction of the islands; the
islands with the stronger moire corrugation show the perpendicular
magnetization, and the ones with the weaker moire corrugation do the in-plane.
Density functional theory calculations reproduce the relationship and explain
the differences between the two types of the islands with an fcc stacking fault
in the intrinsic hcp stacking of cobalt.
