Abstract
The optical conductivity spectra of alkaline-earth-filled skutterudites with the chemical formula (; ) and a reference material were obtained and compared with the corresponding band-structure calculations and with calculated spectra to investigate their electronic structures. At high temperatures, the energy of the plasma edge decreased with the increasing valence of the guest atoms in the cage indicating hole-type conduction. A narrow peak at with a pseudogap was observed in , while the corresponding peaks were located at 200 and 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 spectra directly affects the thermodynamical properties. The band-structure calculation implies that the different electronic structures among these compounds originate from the different states of the ions.
- Received 5 February 2007
DOI:https://doi.org/10.1103/PhysRevB.75.245106
©2007 American Physical Society