Spin-polarised electron studies of low-dimensional magnetic systems

Spin-polarised electrons provide unique experimental access to magnetic pro perties of surfaces and layered structures. The combined use of different t echniques allows us to develop a microscopic picture of the physics underly ing the macroscopic magnetic properties, e.g. magnetic phase transitions, m agnetic coupling phenomena, exceptional surface magnetic properties. In thi s paper, two techniques are described together with the kind of questions a ddressed by them. Spin-resolved appearance potential spectroscopy gives loc al magnetic information about multi-component systems by probing the spin-d ependent local density of unoccupied states. Spin-resolved inverse photo-em ission measures specific electron states above the Fermi level. In particul ar, two-dimensional states serve as magnetic sensors at surfaces. Examples from surfaces as well as thin-film structures of band and local-moment ferr omagnets are presented.