Magnetic anisotropy of 3d transition metal clusters and ultrathin films

The magnetic anisotropy energy (MAE) and related electronic properties of 3d transition-metal (TM) clusters and ultrathin films were determined by calculating self-consistently the effects of the spin-orbit coupling on the spin-polarized charge distribution and on the electronic spectrum for different orientations of the magnetization. The MAE of small clusters shows a complicated non-perturbative behavior as a function of cluster size, structure, bond-length and d-band filling. In agreement with experiment, the MAE is found to be considerably larger in the small clusters than in the corresponding crystals, and often even larger than in thin films. Remarkably, the in-plane anisotropy can be of the same order of magnitude as the off-plane anisotropy. Results for the magneto-anisotropic properties of b.c.c.-(110) monolayers and bilayers are also given. For these films, we find an important in-plane magnetic anisotropy, which is very sensitive to the d-band filling, the exchange splitting and the film thickness.