Bulk and surface electronic structures of CePdX(X=As,Sb) studied by 3d-4f resonance photoemission

We have performed Ce 3d-4f resonance photoemission spectroscopy (RPES) for CePdAs and CePdSb and compared the results with those of Ce 4d-4f RPES. The 3d-4f RPES spectra are remarkably different from the 4d-4f RPES spectra, s howing the smaller contribution of the surface electronic structures in the 3d-4f RPES. On the other hand, the 3d-4f and 4d-4f resonance-minimum spect ra for CePdSb are well described by the band-structure calculations for LaP dSb by taking the photoionization cross sections into account. This indicat es that the surface effect is negligible in the resonance-minimum spectra. The theoretical calculation based on the single-impurity Anderson model wel l reproduces the surface- and bulk-sensitive Ce 4f spectra of both compound s, revealing that the difference between the surface and bulk electronic st ates originates mainly from the surface core-level shift of the bare 4f lev el. The spectral difference between the two compounds is explained by the d ifferent energy dependence of the hybridization strength.