Inelastic X-ray Scattering of Heavy Fermion Compounds ROs4Sb12 (R: Light Rare-Earth)

Abstract

Inelastic X-ray scattering experiments were carried out in the series of filled skutterudites ROs4Sb12 (R: light rare-earth). Phonon energy of the rare-earth guest modes in the longitudinal (1 0 0) direction decreases with increase of atomic number of rare-earth elements from La to Sm inserted into a Sb cage. This fact demonstrates that the guest mode energy is affected by the ionic radius of the rare-earth atom. In addition, comparison between inelastic X-ray scattering and X-ray diffraction experiments reveals the correlation of the guest mode energy in the longitudinal (1 0 0) direction and the Einstein temperature obtained by the temperature dependence of the atomic displacement factor.