Unoccupied spin-split surface state on Co(0001): experiment and theory

We report on spin-resolved inverse photoemission data from Co(0001). In particular, we identified an unoccupied crystal-induced surface state located at <(<Gamma>)over bar> 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. (C) 2001 Elsevier Science B.V. All rights reserved.