Spin-dependent surface band structure of hcp Co(1010)

We report on a detailed analysis of the unoccupied spin-dependent surface band structure of hcp-Co(1010) using inverse photoemission with longitudinally spin-polarized electrons. At the boundary of the surface Brillouin zone Y, an n=l image-potential state is observed, which is split by 0.6 eV into an antisymmetric n=1(-) and a symmetric n=1(+) state, reflecting the high corrugation in front of the "open" hcp (1010) surface. The upper n=1(+) state is nearly dispersionless in contrast to earlier predictions. Majority and minority crystal-induced surface bands, exchange split by 0.5 eV due to appreciable sd hybridization at the LI point of the unoccupied hcp Co band structure, exhibit almost equal effective masses. [S0163-1829(99)00127-7].