Simple band model for La sub 1-x Sr sub x CoO sub 3 : Evidence from electron spectroscopy

Valence band photoelectron spectra and high resolution electron energy loss spectra for La{sub 1-x}Sr{sub x}CoO{sub 3} (x {le} 0.5) have been measured. The general appearance and variation with photon energy of the former may be interpreted in terms of the density of states arising from a simple semiempirical tight binding band structure calculation, for reasonable values of Hamiltonian matrix elements. The latter show a highly damped loss feature below 1 eV which may be assigned to a plasma oscillation whose frequency is overestimated by the same calculations, indicating a considerable enhancement of effective mass through correlation.