Resonant inverse photoemission study of CeCoGe 3− xSi x

Abstract

We have measured the resonant inverse photoemission spectra (RIPES) of CeCoGe 3−x Si x (0⩽x⩽3) as functions of composition and temperature. The strong composition dependence of 4f-state just above the Fermi level ( E F) shows that the localized 4f electrons in the compound become itinerant due to the enhanced Kondo effect. Temperature dependence of the f 1-peak indicates a transition from the paramagnetic state at room temperature to a coherent Fermi-liquid regime at low temperatures. The most remarkable variation of the spectra has been observed above 200 K with increasing temperature in CeCoSi 3 which has a very high Kondo temperature T K of about 900 K. This suggests that the change in the 4f-electronic state of CeCoSi 3 may be scaled by the coherence transition temperature rather than T K.