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The Ce 4 f surface shift: A test for the Anderson-impurity Hamiltonian

1996; American Physical Society; Volume: 54; Issue: 24 Linguagem: Inglês

10.1103/physrevb.54.r17363

1095-3795

Lamberto Duò, Stefano Rossi, P. Vavassori, F. Ciccacci, G.L. Olcese, G. Chiaia, I. Lindau,

Nuclear physics research studies

Evidence is provided of the role of the different hybridization strengths between the surface and the bulk in determining the magnitude of the surface shift for the shallow Ce $4f$ levels, with respect to the deeper core levels. This was achieved by comparing the photoemission core levels for a weakly hybridized case (CeAl) to a case of intermediate hybridization ($\ensuremath{\gamma}$-Ce). For CeAl a $4f$ surface shift of 0.45 eV was observed, similar to that for the $5p$ core level, whereas a smaller (if any) $4f$ surface shift was observed for $\ensuremath{\gamma}$-Ce. Model calculations based on the Anderson impurity Hamiltonian are shown to give a correct evaluation of this effect, which can be exploited as a way of testing the results of such a description for the Ce $f$ states.