Direct Observation Of Valence Transition In Ceni1-Xcoxsn Alloys By X-Ray And Photoelectron Spectroscopies

We investigated the electronic structure of CeNi1-xCoxSn (x=0.33 and 0.38) as a function of temperature, combining x-ray absorption spectroscopy in the partial fluorescence yield, resonant x-ray emission spectroscopy, and photoelectron spectroscopy. The three spectroscopic techniques provided complementary and consistent information. For x=0.33, the valence transition into a mixed-valence regime is deduced to take place around 60 K, as seen from the enhancement of the f(0) and f(2) components and the relative suppression of the f(1) component. The valence was stable for x=0.38 for temperatures down to 17 K. The resonant inelastic x-ray scattering was also performed for x=0.33 at 17 K, suggesting localized or partially delocalized f states. Kondo peak was observed in the resonant valence spectra, showing the existence of the c-f hybridization. The mechanism of the valence transition is discussed.