Mapping the spin-dependent electron reflectivity of Fe and Co ferromagnetic thin films

Spin polarized low energy electron microscopy is used as a spin-dependent spectroscopic probe to study the spin-dependent specular reflection of a polarized electron beam from two different magnetic thin film systems: Fe/W(110) and Co/W(110). The reflectivity and spin-dependent exchange-scattering asymmetry are studied as a function of electron kinetic energy and film thickness, as well as the time dependence. The largest value of the figure of merit for spin polarimetry is observed for a five monolayer thick film of Co/W(110) at an electron kinetic energy of 2 eV. This value is 2 orders of magnitude higher than previously obtained with state of the art mini-Mott polarimeter. We discuss implications of our results for the development of an electron-spin-polarimeter using the exchange-interaction at low energy.