Einstein modes in the phonon density of states of the single-filled skutterudite Yb0.2Co4Sb12

I. K. Dimitrov, M. E. Manley, S. M. Shapiro, J. Yang, W. Zhang, L. D. Chen, Q. Jie, G. Ehlers, A. Podlesnyak, J. Camacho, and Qiang Li
Phys. Rev. B 82, 174301 – Published 10 November 2010

Abstract

Measurements of the phonon density of states by inelastic neutron time-of-flight scattering and specific-heat measurements along with first-principles calculations, provide compelling evidence for the existence of an Einstein oscillator (rattler) at ωE15.0meV in the filled skutterudite Yb0.2Co4Sb12. Multiple dispersionless modes in the measured density of states of Yb0.2Co4Sb12 at intermediate transfer energies (14ω20meV) are exhibited in both the experimental and theoretical density of states of the Yb-filled specimen. A peak at 12.4 meV is shown to coincide with a second Einstein mode at ωE212.8meV obtained from heat-capacity data. The local modes at intermediate transfer energies are attributed to altered properties of the host CoSb3 cage as a result of Yb filling. It is suggested that these modes are owed to a complementary mechanism for the scattering of heat-carrying phonons in addition to the mode observed at ωE15.0meV. Our observations offer a plausible explanation for the significantly higher dimensionless figures of merit of filled skutterudites, compared to their parent compounds.

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  • Received 20 May 2010

DOI:https://doi.org/10.1103/PhysRevB.82.174301

©2010 American Physical Society

Authors & Affiliations

I. K. Dimitrov1,*,†, M. E. Manley2, S. M. Shapiro1, J. Yang3, W. Zhang3, L. D. Chen3, Q. Jie1, G. Ehlers4, A. Podlesnyak4, J. Camacho1, and Qiang Li1,*,‡

  • 1Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973-5000, USA
  • 2Lawrence Livermore National Laboratory, Livermore, California 94551, USA
  • 3State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China
  • 4Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6475, USA

  • *Corresponding author.
  • idimitrov@bnl.gov
  • qiangli@bnl.gov

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Issue

Vol. 82, Iss. 17 — 1 November 2010

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