Lattice dynamics and anomalous softening in the YbFe4Sb12 skutterudite

Möchel, A.; Voigt, J.; Sergueev, I.; Hermann, R.; Stone, M. B.; Guguchia, Z.; Prager, M.; Sales, B. C.; Shengelaya, A.; Wille, H.-C.; Keppens, V.

doi:10.1103/PhysRevB.84.184306

Journal Article

Lattice dynamics and anomalous softening in the YbFe4Sb12 skutterudite

Möchel, A.FZJ* ; Sergueev, I. ; Wille, H.-C. ; Voigt, J.FZJ* ; Prager, M.FZJ* ; Stone, M. B. ; Sales, B. C. ; Guguchia, Z. ; Shengelaya, A. ; Keppens, V. ; Hermann, R.FZJ*

2011
APS College Park, Md.

Physical review / B 84(18), 184306 (2011) [10.1103/PhysRevB.84.184306]

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Please use a persistent id in citations: http://hdl.handle.net/2128/10899 doi:10.1103/PhysRevB.84.184306

Abstract: The lattice dynamics of the filled skutterudite YbFe4Sb12 was studied by resonant ultrasound spectroscopy and an anomalous softening in the temperature dependence of the elastic constants at similar to 50 K was observed. This anomaly can not be explained by the dynamics of the filler, in contrast to other filled skutterudites. We have further investigated the origin of this anomaly using macroscopic and microscopic measurements. A rearrangement of the spectral weight of the Yb phonon states was observed in the temperature dependence of the density of phonon states, obtained by inelastic neutron scattering. We suggest that the anomaly is due to a change of the Yb valence state and that the anomaly and the phonon spectral weight rearrangement have the same origin.

Keyword(s): Basic research (1st) ; Others (1st) ; Condensed Matter Physics (2nd) ; J

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Physics, Condensed Matter

Note: We thank Dr. D. Robinson and Mr. D. Bessas for their support during the synchrotron radiation measurements and Professor H. Schober and Dr. M. M. Koza for helpful discussions. We thank Professor F. Grandjean and Dr. L. Rebbouh for their help during the Mossbauer spectral measurements. The European Synchrotron Radiation Facility, the Advanced Photon Source, and the Spallation Neutron Source are acknowledged for provision of synchrotron and neutron beam time at the nuclear resonance station ID18 and ID22N, the high-energy station 6-ID-D and the wide Angular-Range Chopper Spectrometer, respectively. R.H. acknowledges support from the Helmholtz University Young Investigator Group "Lattices Dynamics in Emerging Functional Materials." Work at The University of Tennessee was supported by NSF Grant DMR-0804719. BCS acknowledges support from the 'Materials Sciences and Engineering Division', Office of Science, US Department of Energy. A portion of this research at Oak Ridge National Laboratory's Spallation Neutron Source was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, US Department of Energy.

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