Surface magnetism: From the spin-resolved density of states to magnetic domain imaging on the nanometer scale

Making use of the information depth of only a few layers for electrons with low kinetic energies, photoemission experiments, with an additional measur ement of the electron spin polarization or with excitation using circularly polarized radiation, allow one to determine whether adatoms change the mag netic properties at the surface and whether they "feel" the magnetism of th e underlying substrate. This is investigated for oxygen adsorbed on Fe(110) and Co (0001). Enhanced surface sensitivity can be gained in tunneling exp eriments. The technique of spin-polarized metastable deexcitation spectrosc opy thus enables one to determine the spin-resolved density of states in th e near-surface region. By making the highly lateral resolving scanning tunn eling microscope sensitive to the electron spin polarization it becomes pos sible to image magnetic domains on the nanometer scale; this is demonstrate d for Gd (0001) surfaces.