ORIGIN OF ORBITAL MAGNETIZATION AND MAGNETOCRYSTALLINE ANISOTROPY IN TX ORDERED ALLOYS (WHERE T=FE,CO AND X=PD,PT)

We present a method to calculate the magnetic anisotropy parameters which is based on a perturbative treatment of the spin-orbit interaction and a Green's function technique in real space. it allows us to interpret the magnetocrystalline anisotropy energy (MAE) in terms of interatomic interactions in the crystal. The method is applied to analyze orbital magnetism and MAE in TX ordered alloys (T=Fe,Co and X=Pd,Pt). The convergence of the orbital moments and MAE in real space and its relation to the problems of Brillouin-zone integration and of oscillatory behavior of MAE as a function of band filling are discussed. A comparison with results obtained by other methods is also given.