<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mn>4</mml:mn><mml:mi>f</mml:mi></mml:math>-Derived Resonant Photoemission in the Early Rare Earths: Possible Evidence for Localized Screening Channel

Abstract

Photoemission studies of $\mathrm{RE}{\mathrm{Ru}}_{2}$ and $\mathrm{RE}{\mathrm{Pd}}_{2}$ ($RE=\mathrm{C}\mathrm{e},\phantom{\rule{0ex}{0ex}}\mathrm{P}\mathrm{r},\phantom{\rule{0ex}{0ex}}\mathrm{N}\mathrm{d}$) reveal two $4f$-derived features with an energy separation of \ensuremath{\sim}2.5 eV, which move in parallel to larger binding energies in going from Ce to Pr to Nd. These results, which are at variance with predictions of Anderson-model treatments based on the large-orbital-degeneracy approximation, are compatible with the treatments of Liu and Ho and of Riseborough, who distinguished between the two peaks on the basis of their screening geometries.