We have measured x-ray magnetic circular dichroism spectra at the Co and Pt L2,3-edges in Co80Pt20 perpendicular magnetization films, wherein the uniaxial magnetic anisotropy constant, Ku, significantly increases with decreasing film thickness, δ, and reaches 1.7×107erg/cm3 for δ=3nm. The anisotropy of the orbital magnetic moment (AOM) was estimated as a function of δ, and the relationship between AOM and Ku is discussed. When the thickness was reduced, the AOM for Pt 5d was nearly constant, whereas a weak increase was observed for Co 3d. Both AOMs are small in contrast to the large Ku, and any proportionality between AOM and Ku was hardly recognized. This result indicates that a large AOM is not always a necessary and sufficient condition for the appearance of perpendicular magnetization.

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