Unoccupied spin-split surface state on Co(0 0 0 1): experiment and theory

We report on spin-resolved inverse photoemission data from Co(0 0 0 1). In particular, we identified an unoccupied crystal-induced surface state located at Γ in the surface Brillouin zone. The surface state exhibits an exchange splitting of 0.66±0.03 eV with both majority and minority parts located in energy above the Fermi level. The experimental data are compared with bandstructure and spin-polarized inverse-photoemission calculations, which we obtained in the framework of a fully relativistic one-step theory developed for ferromagnetic materials. Both experiment and theory agree in locating the minority as well as the majority components of the surface state above the Fermi level.