High‐energy Surface Spin Waves Studied by Spin‐polarized Electron Energy Loss Spectroscopy

Abstract

Abstract In this chapter, studies of high wave‐vector spin waves at surfaces are discussed. At present, the only technique that allows experimental access to this type of spin waves is spin‐polarized electron energy loss spectroscopy (SPEELS). In this experiment, a beam of spin‐polarized, monochromatic electrons is scattered from a magnetic sample. The scattered electrons are analyzed with respect to their wave vector and energy transfer to the sample. The excitation of spin waves results in specific loss features in the SPEEL spectra, as is shown on the example of three different systems, fcc Co on Cu(001), hcp Co on W(110), and tetragonal distorted thin Fe films on Co/Cu(001). In all three systems, the spin waves show a pronounced dispersion, that is, a dependence of the spin‐wave energy on the wave vector, which allows conclusions about the exchange interaction at the topmost surface layers. The spin‐wave loss features in the spectra also show a large intrinsic width that results from the strong damping of these excitations by the decay into electron–hole pairs. In this chapter, the results obtained by SPEELS are also compared to data measured by complementary experimental techniques and recent theoretical calculations.