The motion of guest Gd ions in oversized boron cages in GdB 6 was investigated from phonon spectra measurements obtained by inelastic x-ray scattering. The measured phonon modes soften by about 10% from 300 K down to T N=16 K, in particular, the longitudinal phonon for the propagation vector q 1=(1/2,0,0) that characterizes the distorted structure below T N. Besides, the dispersion relation curves show kinklike anomalies at q k=(0.38,0.38,0). The observed results imply that the motion of the guest Gd ion interplays with the f electrons magnetoelastically and with carriers via Fermi surface nesting. The anomalous properties previously reported for this material far above T N originate from the strong electron-phonon coupling, which causes the motion of guest ions as precursors to the first-order phase transition.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 2011 Dec 28|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics