Investigation of spin and orbital moments of L1 ₀ FePtRh thin films

Fe ₅₀Pt _50-xRh _x films have attracted much interest recently due to their potential usage in heat assisted magnetic recording media and the ferromagnetic (FM) to antiferromagnetic (AFM) transition as Rh concentration is increased. In this study, we present an investigation of the spin moment (m _s) and orbital moment (m _l) of Fe in Fe ₅₀Pt _50-xRh _x films using x-ray magnetic circular dichroism. The measurements were made in the soft x-ray region along the film normal, which corresponds to the easy axis of the (001) textured L1 ₀ FePt with uni-axial magnetic anisotropy. They show that the magnetic moment of Fe mainly contributes to the whole magnetization of the films. The decrease of m _l with Rh doping concentration implies a decrease of magneto-crystalline anisotropy, whereas the significant decrease of m _s is consistent with the FM to AFM transition at above 15 at. of Rh.