Electronic hybridization effect on4felectron crystal field states ofPrOs4P12

Abstract

Crystal-field excitation spectra of $\text{Pr}\text{ }4f$ electron state in the filled skutterudite ${\text{PrOs}}_{4}{\text{P}}_{12}$ measured by inelastic neutron scattering experiment evolve distinctly with temperature variation. The spectral widths of excitations from the ground-state singlet to the two triplets and their temperature dependences are well reproduced by the theory based on the exchange coupling between $4f$ and conduction electrons. The shift of level energies by around 1 meV below 60 K indicates modification of crystal-field potential with variation of thermal population of $4f$ electron crystal-field states. The spectral evolution is consistent with the specific heat data that deviates from the calculated one for the well-localized $4f$ electron. The result supports the effect of $p\text{\ensuremath{-}}f$ hybridization between $\text{Pr}\text{ }4f$ and $\text{P}\text{ }p$ states in ${\text{PrOs}}_{4}{\text{P}}_{12}$.