Interface structure and perpendicular magnetic anisotropy in Pt/Co multilayers

Pt/Co multilayers sputter-deposited in Ar and Xe ambients, and periodic multilayers composed of specific combinations of Pt, Pd, and Co layers, were grown to study the effects of energetic backscattered Ar neutrals on the interface structure. The effects were correlated with the magnetic and magneto-optical properties with emphasis on the perpendicular magnetic anisotropy, K⊥. Films were characterized by high-resolution transmission electron microscopy, x-ray diffraction including grazing incidence geometry, and magnetic circular x-ray dichroism techniques as well as by standard magnetic and magneto-optic methods. It is found that the perpendicular magnetic anisotropy is extremely sensitive to the degree of intermixing, sharp interfaces yielding the largest anisotropy. The three to fourfold difference in K⊥ found between Ar and Xe sputtered films can be directly correlated to the magnitude of the orbital moment contribution 〈LZ〉 in the Co. This orbital contribution is found to be strongly sensitive to the interface sharpness in the films.