Finite Temperature Magnetism in Gd: Evidence against a Stoner Behavior

The temperature dependence of the rare-earth valence bands has been regarded as a realization of the Stoner behavior. The exchange splitting of the electronic states appears to scale as the magnetic order parameter for $T<\mathrm{}{T}_C$ and to vanish at ${T=T}_C$. We report here a spin-resolved photoemission study on the evolution of Gd bulk bands for $0.5\le {T/T}_C\le 1$. The spin-polarized spectral line shapes display a complex temperature dependence, which clearly contrasts with the interpretation of previous experimental results. The spin-resolved photoemission data demonstrate the inadequacy of the Stoner model to the description of magnetism in rare earths.