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

Abstract

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 $6s$,$5{d}_{{z}^{2}}$-type band (${\ensuremath{\Gamma}}_{4}^{\ensuremath{-}}$ at ${E}_{F}\ensuremath{-}1.4$ eV and ${\ensuremath{\Gamma}}_{1}^{+}$ at ${E}_{F}\ensuremath{-}2.8$ eV) and a critical point of a final-state band (${\ensuremath{\Gamma}}_{4}^{\ensuremath{-}}$ at ${E}_{F}+6.6$ eV) in qualitative agreement with band calculations. At the zone boundary $5d$ states are observed along the $\mathrm{ML}$ line at about ${E}_{F}\ensuremath{-}0.35$ eV corresponding to an ${L}_{1}$ 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\ifmmode\pm\else\textpm\fi{}0.1 eV.