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 measurement of the electron spin polarization or with excitation using circularly polarized radiation, allow one to determine whether adatoms change the magnetic properties at the surface and whether they “feel” the magnetism of the underlying substrate. This is investigated for oxygen adsorbed on Fe (110) and Co (0001). Enhanced surface sensitivity can be gained in tunneling experiments. The technique of spin-polarized metastable de-excitation spectroscopy thus enables one to determine the spin-resolved density of states in the near-surface region. By making the highly lateral resolving scanning tunneling microscope sensitive to the electron spin polarization it becomes possible to image magnetic domains on the nanometer scale; this is demonstrated for Gd (0001) surfaces. Received: 28 April 2000 / Accepted: 4 September 2000 / Published online: 7 March 2001