Temperature-dependent exchange splitting of unoccupied electronic states in Gd(0001)

Inverse photoemission with variable photon energy reveals the presence of an empty surface state on Gd(0001)Γ¯, which shifts towards the Fermi energy (${\mathit{E}}_{\mathit{F}}$) with increasing temperature. Hereby, the surface state leads to a significant increase in the d-like density of states at ${\mathit{E}}_{\mathit{F}}$, suggesting its involvement in the enhanced magnetic coupling in the topmost surface layer of Gd(0001). A temperature-dependent exchange splitting is also observed for the empty 5d band that seems to vanish only well above the bulk Curie temperature.