The effects of chemical ordering in thin film ${\mathrm{Fe}}_{0.5}{\mathrm{Pd}}_{0.5}$ alloys, deposited by molecular-beam epitaxy directly on a MgO (001) substrate, have been studied using magnetic circular x-ray dichroism (MCXD) at the Pd and Fe $L_{2,3}$ edges. This system exhibits perpendicular magnetic anisotropy if grown in the ${L1\mathrm{}}_0$ (001) phase and in-plane anisotropy in the disordered $\gamma$ phase. We show that MCXD is a sensitive tool for studying variations in the spin and orbital magnetic moments due to changes in the chemical order. We obtain quantitative results for spin and orbital anisotropies and their variations with chemical order in the ${\mathrm{Fe}}_{0.5}{\mathrm{Pd}}_{0.5}$ alloy system.

• Received 24 February 1998

DOI:https://doi.org/10.1103/PhysRevB.59.1105