Spin-polarized photoemission studies of the exchange splitting of the Gd 5delectrons near the Curie temperature

Spin-polarized photoemission was employed to investigate the temperature dependence of the exchange splitting of Gd(0001) for both the surface state near the Fermi level ${\mathit{E}}_{\mathit{F}}$ and the 5d bulk bands. The bulk bands at 1–2 eV below ${\mathit{E}}_{\mathit{F}}$ show Stoner-like behavior where two peaks with opposite spin polarization shift toward each other as the temperature increases. In contrast, the temperature dependence of the surface state indicates spin-mixing behavior due to fluctuating local moments. These differences are attributed to the degree of itinerancy of the 5d electrons in the two cases.