Bulk 4<i><i>f</i></i> Electronic States of Ce-Based Heavy Fermion System Probed by High-Resolution Resonance Photoemission

Abstract

“Bulk-sensitive” Ce 3 d -4 f resonance photoemission (RPES) with an unprecedentedly high resolution has revealed a clear difference of bulk Ce 4 f spectral weights of heavy fermion system CeRu 2 Si 2 and CeRu 2 Ge 2 in the region of the tail of the Kondo peak and its spin-orbit partner. The significant spectral difference in both materials is in strong contrast to the mutually similar “surface-sensitive” 4 d -4 f RPES. The obtained bulk-sensitive spectra are well reproduced by a single impurity model. Consideration of the crystalline electric field splitting is important for estimating a realistic Kondo temperature from the bulk 4 f spectra.