Spin Polarization of Photoelectrons from Cesiated Fe, Co, and Ni

Abstract

The electron-spin polarization (ESP) of photoelectrons from cesiated Fe, Co, and Ni films has been measured for photon energies $h\ensuremath{\nu}<6$ eV at 4.2\ifmmode^\circ\else\textdegree\fi{}K. The photo-ESP was positive (magnetic moment parallel to the magnetization) independently of Cs coverage and photon energy. For Ni and Co and coverage parameters $\ensuremath{\theta}$ near to 1 (monoatomic layer) the photo-ESP approaches 0 at photon energies near the photothreshold $\ensuremath{\Phi}$. However with Fe, the photo-ESP is rather independent of $\ensuremath{\theta}$, even for $h\ensuremath{\nu}$ approaching $\ensuremath{\Phi}$. At higher photon energies a common trend of the spectra is observed: The photo-ESP approaches the average polarization $P=\frac{{n}_{B}}{n}$ with photon energies exceeding $\ensuremath{\Phi}$ only by 2 to 3 eV, which correlates with the $d$ bandwidth observed in recent ultraviolet photoemission and x-ray photoemission spectroscopy.