UC San Diego

Results for two categories of filled skutterudites that have previously received limited attention are presented: (1) single crystals of the As-based filled skutterudites and (2) thin films of the Sb-based filled skutterudites. We show that the compounds CeT₄As₁₂ (T = Ru, Os) exhibit non-Fermi liquid and Kondo insulator behavior, respectively. The phenomena seen in these materials is discussed in terms of strong hybridization between the localized f-electron states and the conduction electron states, with various perturbing factors Results for thin films of the compounds PrFe₄Sb₁₂ and YbFe₄Sb₁₂, which were synthesized by the pulsed laser deposition technique, are also presented. Measurements of the PrFe₄Sb₁₂ specimens indicate that the films are single phase and exhibit behavior that is comparable to that seen in bulk specimens. To explore the affect of film thickness, YbFe₄Sb₁₂ specimens were synthesized where t was varied from 6000 to 300 Å. Thick films (t > 1000 Å) show electrical transport behavior similar to that seen for bulk specimens. A metal to insulator transition is observed for thin films (t < 1000 Å) which is correlated with film topology