Electronic structure theory of magnetism of surfaces, interfaces and overlayers

It is now clear that the advent of accurate self-consistent (local) spin density function (LSDF) calculations for surfaces, interfaces, and multilayers means that theory is no longer limited to simple parameter-dependent models. These complex magnetic systems are of growing interest because the reduced symmetry, lower coordination number, and availability and role of highly localized surface and interface states offers the possibility of inducing new and exotic phenomena and so holds out the promise of new device applications. A key question and goal has been the possibility of inducing 2D magnetism in a controlled way. We describe some methods used to obtain structural, electronic and magnetic properties and how these calculations can give not only a clearer understanding of the experimental results but also predictions on novel systems not yet made experimentally. In particular, the magnetization (including its anisotropy) and charge and spin densities obtained can be compared directly with experiments (e.g., conversion electron Mössbauer spectroscopy). For excitations (like spin-polarized photoemission and inverse photoemission), spin polarized photocurrents can be calculated from the LSDF results. Illustrative examples demonstrate that it is possible not only to make quantitative predictions for real systems, but more importantly, one gains insight into the underlying physics of these materials.