Photoemission and electronic structure of cobalt

Abstract

Energy distribution curves (EDC's) of photoelectrons emitted normal to the surface have been measured for the (0001) and (10¯10) single crystal faces and for evaporated polycrystalline films of cobalt. Incident photon energies of 11.83, 16.85, and 21.22 eV were used. The EDC's of the (0001) and (10¯10) faces can be interpreted in terms of emission from electronic states characteristic of the one-dimensional bulk band structure along the corresponding symmetry lines. The maximum density of occupied states of the entire Brillouin zone is found to occur at —0.35 ± 0.05 eV relative to the observed Fermi level. The density of states $N\left(E\right)\mathrm{}$ for the ferromagnetic fcc phase has been calculated self-consistently by applying the Hubbard-model Hamiltonian. $N\left(E\right)\mathrm{}$ at the Fermi level is obtained to be 0.65 and 0.99 electron/(atom eV) for the majority-spin and minority-spin states, respectively. The calculated $N\left(E\right)\mathrm{}$ is consistent with the overall shapes of ultraviolet and x-ray photoelectron spectra. The present experimental and theoretical results agree with the requirements of the itinerant-electron model of ferromagnetism of the Slater-Stoner-Wohlfarth theory below the Curie point.