Adatom-induced spin reorientation transitions and spin canting in Co films on a stepped Cu(001) surface

We have investigated spin reorientation transitions on ultrathin Co films grown on a stepped Cu(1 1 17) surface upon adsorption of Ag and NO by means of the magneto-optical Kerr effect, the magnetization-induced second harmonic generation, x-ray magnetic circular dichroism, and laser excited photoemission magnetic circular dichroism. Although a spin reorientation transition from the step parallel to perpendicular direction is well known to occur after Ag deposition, the magnetization after the transition is found to be canted from the film plane toward the terrace atomic plane. On the other hand, upon NO adsorption, the Co film is shown to lose its inherent twofold uniaxial magnetic anisotropy without showing canted magnetization.