Abstract
The atomic dynamics of the guest modes in heavy fermion filled skutterudites OsSb were investigated by inelastic x-ray scattering. Comparison of the phonon dispersion relations for the filled skutterudite SmOsSb with those for the unfilled skutterudite IrSb indicates that the guest modes in filled skutterudites are observed as additional modes in the unfilled skutterudites. The dispersion relations for IrSb and SmOsSb agree reasonably well with the results obtained by ab initio calculations for IrSb and LaOsSb, respectively. The rare-earth dependence of the inelastic x-ray scattering spectrum in the series of OsSb compounds is difficult to interpret in terms of changes in the atomic mass and electron number of the rare-earth atom inserted into the Sb cage. The combination of inelastic x-ray scattering and x-ray absorption spectroscopy reveals a correlation between the guest mode energy and the guest free space in these compounds. The rare-earth dependence of the inelastic x-ray scattering spectrum indicates the mediation of heavy fermion behavior by the atomic motion of the guest in some OsSb compounds and the electron-phonon coupling between the guest modes with 4-electrons and conduction electrons in the series of OsSb compounds.
4 More- Received 28 June 2012
DOI:https://doi.org/10.1103/PhysRevB.86.195115
©2012 American Physical Society