Superconducting Properties of LaRu4As12 synthesized at high pressure

We report on the systematic evolution of superconducting properties in filled skutterudite LaRu4As12 (T-c = 10.3 K) from the resistivity and specific heat experiments. Ternary La-based filled skutterudite LaRu4As12 is synthesized by the high pressure synthesis method. LaRu4As12 shows a superconducting phase transition at 10.3 K. The electronic specific heat coefficient (gamma) and phonon part of the specific heat coefficient (beta) are gamma = 57 mJ/K-2 mol and beta = 0.734 mJ/K-2 mol for LaRu4As12. The upper critical field H-c2 becomes similar to 9.6 T. The upward deviation of the determined mu H-0(c2) curve from the BCS fitting suggests multiband effect in LaRu4As12.