Inelastic neutron scattering study on 4f-electron multipole system PrTr2X20 (Tr: transition metal, X: Al and Zn)

We have conducted inelastic neutron scattering measurements to investigate the crystal-electric-field (CEF) levels associated with Pr³⁺$4f^2$-electron configuration in the PrTr₂X₂₀ (Tr: transition metal, X: Al and Zn). Hybridization between conduction electrons and $4f$ electrons has been deduced from the spectral widths, which is a key factor for understanding the anomalous low-temperature transport properties and the ordering phase transitions in the PrTr₂X₂₀. We also discuss structural-transition effects on local symmetries of the Pr-ion sites.