EVIDENCE FOR STONER-LIKE BEHAVIOR OF THE SURFACE-STATE ON GD(0001)

We report on angle-resolved photoemission and inverse photoemission st udies of Gd(0001) in the temperature range 60 to 400 K. It is found th at with increasing temperature both occupied and unoccupied parts of t he d-like surface state at <(Gamma)over bar> shift towards the Fermi l evel. This rules out a pure spin-mixing behavior with constant exchang e splitting as claimed recently on the basis of spin-resolved PE data. Instead, the temperature variation of the surface-state exchange spli tting is better described by a Stoner-like behavior, with an enhanced surface Curie temperature. Nevertheless, a small residual splitting ab ove T-c of the order of 100 meV cannot be ruled out.