Correlation of magnetocrystalline anisotropy of Fe0.5Pd0.5 alloy with chemical order

We study the magnetocrystalline anisotropy of Fe0.5Pd0.5 alloy using the fi rst-principles spin-polarized relativistic Korringa-Kohn-Rostoker coherent- potential approximation. We investigate the effect of long-ranged chemical order on the magnitude as well as the direction of easy magnetization. We f ind that in this alloy, the chemical order enhances the magnitude of the ma gnetocrystalline anisotropy energy as well as altering the easy axis. In pa rticular, for the L1(0) ordered alloy the easy axis is perpendicular to the alternating layers of Fe and Pd with quite large magnetocrystalline anisot ropy energy 124 mu eV. These observations are in very good agreement with e xperiments. We also find that it is the electronic structure in the vicinit y of the Fermi surface that is responsible for this effect.