Electronic structure of R₂PdSi₃ (R=La, Ce, Gd, and Tb) compounds

Abstract

Photoemission (PE) studies of R₂PdSi₃ (R=La, Ce, Gd, and Tb) compounds are presented and the results are compared with those of band-structure calculations. For the valence band, the spectroscopic results are in full agreement with the calculated band structure and support the earlier proposal that the thermal and transport anomalies in the Gd compound are not related to the Kondo effect, since no sharp feature is found near the Fermi energy (E_F). The contribution to the density of states at E_F is found to be dominated by R 5d, rather than by Pd 4d states, indicating that the surprisingly large thermopower previously observed for the Gd compound at 300 K does not arise from the latter. For the Ce compound, the spectroscopic results establish trivalent character of Ce. An unusual satellite feature around 3 eV at the higher binding energy side of the Si 2p PE signal is tentatively attributed to a "shake-up" effect due to Si 3p-3p sub-band transitions.