Experimental energy bands of a rare-earth metal: Gd(0001)

We have determined energy bands of Gd metal at room temperature with the use of angle-resolved photoelectron spectroscopy with synchrotron radiation. Along the central sixfold axis of the Brillouin zone, we find the two critical points of the $6s$,5d_z²-type band (Γ₄^- at EF-1.4 eV and Γ₁⁺ at EF-2.8 eV) and a critical point of a final-state band (Γ₄^- at EF+6.6 eV) in qualitative agreement with band calculations. At the zone boundary $5d$ states are observed along the ML line at about EF-0.35 eV corresponding to an L₁ point. Unoccupied $4f$ states appear in the secondary-electron emission within 1.6 eV of the vacuum level. The work function of Gd(0001) is 3.3±{}0.1 eV.