X-ray photoemission and resistivity studies of the Pd-covered Ce thin films

We have fabricated Ce/Pd bilayers grown on the SiO$_2$ substrate by magnetron sputtering under ultrahigh vacuum. Usage of palladium layer on top of the Ce film appears to prevent effectively the sample oxidation. The thickness of the cerium films is between 10 - 200 nm and 10 nm-thick palladium overlayers are always used. We have performed $in - situ$ X-ray photoelectron spectroscopy on the as-deposited films and $ex - situ$ electrical resistivity measurements and XRD characterization. XPS confirms a very good quality of the samples. The analysis of the Ce $3d$ spectrum suggests that the $f$ states of Ce are on the border between the fluctuating valence and localization. The resistivity measurements reveal a competition of the Kondo scattering, semiconducting and metallic behaviors as well as the influence of the dimensional effect.