Lattice Instability Coupled With Valence Degrees Of Freedom In Valence Fluctuation Compound Ybpd

Inelastic x-ray scattering (IXS) was used to examine the valence fluctuation compound YbPd at 300 K in the Gamma -X, Gamma-M, X-M, and X-R directions. The obtained spectra and determined phonon dispersion relations demonstrate lattice instabilities related to the successive transitions and correlations between phonon spectra and valence degrees of freedom in YbPd. The low-lying branches in the phonon dispersion relations as well as the broadened linewidths of the IXS spectra observed around the longitudinal X point provide supporting evidence of correlation between a valence-lattice interaction and the successive transitions in YbPd. X-ray absorption spectroscopy was also performed in order to discuss correlations between lattice instabilities and Yb valence degrees of freedom in YbPd.