The origin of this anisotropy is the interaction of the magnetization with the crystal lattice (the spin-orbit coupling). As the spin-orbit coupling is of relativistic origin, the fully-relativistic treatment to the tight-binding Korringa-Kohn-Rostoker (TB-KKR) method was introduced in the first part of this work. In the second part the in-plane magnetization of the Fe surfaces and the magnetic properties of Fe clusters were discussed and a systematic study comparing clusters and surface systems was performed. FePt surface systems with high out-of-plane magnetic anisotropy were investigated in the third part.
In the last part a detailed study of the magnetic anisotropy of thin Fe films on (001) oriented GaAs was presented. In agreement with experiment these films were found to have an in-plane anisotropy with the easy axis along the -direction. In addition, the influence of Au protective layers on magnetic properties of GaAs/Fe was shown and discussed. Also, theoretical results of the spin and orbital magnetization of the Co marker in Fe film on GaAs were compared with the experimental results.