We have investigated the temperature-dependent exchange splitting of d(z2)-
like surface states of Gd(0001) films by scanning tunneling spectroscopy. T
he splitting reduces with increasing temperature. Even at 350 K, a splittin
g of 400 meV remains excluding both, pure spin-mixing and pure Stoner-like
behavior. The simultaneous determination of topography and spectroscopy gua
rantees that no morphology-induced influence is present. (C) 1999 Elsevier
Science B.V. All rights reserved.