Spin Polarized Electron Scattering from and Spin Dynamics of Ultrathin Magnetic Films

Polarized electron beams interacting with the surface via exchange and spin orbit coupling established themselves as a unique tool for studying magnetic and electronic surface properties. We use the multiple scattering theory of the spin polarized low energy electron diffraction (SPLEED) to study the structural and magnetic properties of Fe bilayer on W(001) substrate. We find the spin orbit asymmetry--a measure of the spin orbit coupling--to be very sensitive to the position of the surface ions. On the other hand, the exchange asymmetry--a measure of the exchange coupling between the beam and substrate electrons--proves to be far less sensitive to changes in magnetic properties of the film. Inelastic electron scattering accompanied by the flip of the incoming beam spin is a potentially powerful probe of magnetic excitations in ultrathin films. We have investigated the spin flip component of the diffuse scattering near the bulk critical temperature of an antiferromagnetically ordered surface. Within the Landau-Ginzburg theory we explore the static correlation function. For Cr(110), we then calculate the intensity of both the diffuse peak near T_{c} and the half -order beams. We find the intensities are within the reach of the state of the art experimental techniques. While the total rate of inelastic scattering integrated over the energy loss is controlled by the static correlation function, the energy resolved loss spectrum requires the knowledge of the spin dynamics. There is currently very little understanding of the spin dynamics of itinerant electron magnetic films. We use the one band Hubbard model to study the transverse dynamic susceptibility of films consisting of magnetic layers with ferromagnetic order within the layers parallel to the surface. The coupling between the layers is arbitrary. The nature of the spin waves and Stoner spectrum is investigated and discussed. It is shown that the SPEELS spectrum contains information about the local magnetic properties of the surface layer.