Final-state symmetry effects in photoemission of thin Gd overlayers

Abstract
The 4f valence band and shallow core levels of ultrathin Gd overlayers on Cu(100) and on crystalline nickel overlayers on Cu(100) have been investigated using angle-resolved photoemission. The authors have observed a definite selection of final-state symmetries which, for one-half to four-monolayer-thick Gd films, indicates that the occupied Gd 5d band is predominantly 3z2-r2 and j=3/2 in character. The 5p3/2 appears to be predominantly z in character for thin Gd overlayers on Cu(100). This occurs as a consequence of final-state interactions between the Gd5d and 5p eigenstates. These results, together with the observed screening processes of the photoemission hole state, are discussed and applied to the understanding of photoemission resonance from the valance bands.