Abstract
We present a theory to study the relation between compositional order and magnetocrystalline anisotropy of ferromagnetic alloys. The ordering phenomenon is represented by static concentration waves. The electronic part is described within the spin-polarized relativistic Korringa-Kohn-Rostoker coherent-potential approximation. This scheme can be used to investigate the change in the magnitude as well as the direction of magnetic anisotropy in an alloy at the onset of ordering. The same framework can also be used to study directional chemical order produced by magnetic annealing. We have calculated the magnetocrystalline anisotropy energy of ordered fcc-Co0.5Pt0.5 alloy using this method. We find that the magnetocrystalline anisotropy energy of the ordered phase is two orders of magnitude larger than that of the disordered phase. Also, that the direction of ‘easy’ magnetization in the ordered phase depends on the type of ordering. These results are in good agreement with the experimental observations.