Valence transition of the intermetallic compound Ce2Rh2Ga probed by resonant x-ray emission spectroscopy

We have investigated the Ce valence of an intermetallic compound Ce2Rh2Ga with a phase transition at Tt=128.5 K by means of high-energy resolution fluorescence-detected x-ray absorption spectroscopy (HERFD-XAS) and resonant x-ray emission spectroscopy (RXES) around the Ce L3 edge. The HERFD-XAS spectra in the whole temperature range from 300 to 3 K exhibit weak f0(Ce4+) and f2(Ce2+) peaks as well as the f1(Ce3+) main peak, indicating that the Ce 4f electrons hybridize with the conduction electrons. With decreasing temperature from 125 to 100 K across Tt, the f1 peak is reduced, while the f0 peak is enhanced. Concomitantly, the Ce Lα1 RXES intensity taken at the f2 peak of the HERFD-XAS spectrum decreases. These spectroscopic results indicate that the phase transition at Tt of Ce2Rh2Ga is driven by a valence transition of the Ce ions.