Magnetocrystalline anisotropy in (111)CoPt3thin films probed by x-ray magnetic circular dichroism

Angle-dependent x-ray magnetic circular dichroism experiments have been performed at both the Co and Pt $L_{2,3}$ edges in two epitaxial (111) ${\mathrm{CoPt}}_3$ thin films grown at 690 and 800 K. The analysis of the angular variations of the $3d$ orbital magnetic moment shows two different magnetic behaviors: a strong perpendicular magnetocrystalline anisotropy (PMA) for the film grown at 690 K and an almost isotropic behavior for the film grown at higher temperature. The same analysis at the Pt $L_{2,3}$ edges suggests that the $5d$ electrons play an important role in the PMA. Our results correlate the appearance of PMA with the existence of anisotropic structural effects induced during the codeposition process.