Neutron scattering studies on CeRhSb and PrTSb (T = Rh and Pd) compounds

Inelastic neutron scattering studies have been carried out on the Kondo insulator CeRhSb as well as on PrTSb (T = Rh and Pd) compounds. The low energy neutron scattering spectra of CeRhSb at 2 K show no clear evidence of a gap type excitation. The high energy inelastic spectra of CeRhSb show a broad excitation centered about 35 meV, which is a characteristic of a Ce-based valence fluctuating compound. Inelastic spectra of PrRhSb show a presence of broad crystal field (CF) excitations with over-all crystal field splitting of 25 meV. On the other hand well-defined crystal field excitations corresponding to the 4f² configuration of the Pr³⁺ ion have been observed in PrPdSb. The crystal field parameters have been estimated from an analysis of inelastic neutron scattering data of PrPdSb. Analysis shows that the ground state of the Pr³⁺ ion is a crystal field doublet in this compound. The heat capacity calculated from the CF parameters suggests that the observed peak at 8 K in the heat capacity of PrPdSb is due to the magnetic ordering.