Electronic structure theory of surface, interface and thin-film magnetism

Low dimensional magnetic systems including surfaces, interfaces and thin-films, have attracted a great amount of attention in the past decade because, as expected, the lowered symmetry and coordination number offer a variety of opportunities for inducing new and exotic phenomena and so hold out the promise of new device applications. Local spin density functional (LSDF) ab initio electronic structure calculations played a key role in the development of this exciting field by not only providing a clearer understanding of the experimental observations but also predicting new systems with desired properties. Extensive calculated results reviewed here demonstrate that (1) weakened interatomic hybridization at clean surfaces or interfaces with inert substrates give rise to strong magnetic enhancement and (2) the strong interaction with nonmagnetic transition metals diminishes (entirely in some cases) the ferromagnetism and usually stabilizes the antiferromagnetic configuration. Surprisingly, experimentally observed surface (interface) magnetic anisotropy can be reproduced correctly in the theoretical calculations, although the anisotropy energy is only ∼10^-4-10^-5 eV.