Infrared study on the electronic structure of the alkaline-earth-filled skutterudites AM4Sb12 (A=Sr,Ba; M=Fe,Ru,Os)

Shin-ichi Kimura, Hojun Im, Takafumi Mizuno, Shota Narazu, Eiichi Matsuoka, and Toshiro Takabatake
Phys. Rev. B 75, 245106 – Published 11 June 2007

Abstract

The optical conductivity [σ(ω)] spectra of alkaline-earth-filled skutterudites with the chemical formula A2+M4Sb12 (A=Sr,Ba; M=Fe,Ru,Os) and a reference material La3+Fe4Sb12 were obtained and compared with the corresponding band-structure calculations and with calculated σ(ω) spectra to investigate their electronic structures. At high temperatures, the energy of the plasma edge decreased with the increasing valence of the guest atoms A in the Fe4Sb12 cage indicating hole-type conduction. A narrow peak at 25meV with a pseudogap was observed in SrFe4Sb12, while the corresponding peaks were located at 200 and 100meV in the Ru and Os counterparts, respectively. The order of the peak energy in these compounds is consistent with the thermodynamical properties in which the Os compound is located between the Fe and Ru compounds. This indicated that the electronic structure observed in the infrared σ(ω) spectra directly affects the thermodynamical properties. The band-structure calculation implies that the different electronic structures among these compounds originate from the different d states of the M ions.

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  • Received 5 February 2007

DOI:https://doi.org/10.1103/PhysRevB.75.245106

©2007 American Physical Society

Authors & Affiliations

Shin-ichi Kimura1,2,*, Hojun Im2,†, Takafumi Mizuno2, Shota Narazu3, Eiichi Matsuoka3,‡, and Toshiro Takabatake3,4

  • 1UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585, Japan
  • 2School of Physical Sciences, The Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8585, Japan
  • 3Department of Quantum Matter, ADSM, Hiroshima University, Higashi-Hiroshima 739-8530, Japan
  • 4Institute for Advanced Materials Research, Hiroshima University, Higashi-Hiroshima 739-8530, Japan

  • *Electronic address: kimura@ims.ac.jp
  • Present address: Department of Physics, Sungkyunkwan University, Korea.
  • Present address: Department of Physics, Tohoku University, Sendai, Japan.

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Issue

Vol. 75, Iss. 24 — 15 June 2007

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