Superconducting and Magnetic Properties of Filled Skutterudite Compounds RERu₄Sb₁₂ (RE=La, Ce, Pr, Nd and Eu)

Abstract

We have studied superconducting and magnetic properties of RERu₄Sb₁₂ prepared by an Sb-flux method and found that LaRu₄Sb₁₂ is superconducting below 3.58 K and PrRu₄Sb₁₂ is a Van Vleck paramagnet which becomes superconducting below 1.04 K. CeRu₄Sb₁₂ is a unique substance which shows intermediate-valence behavior with a characteristic broad peak around 100 K in the magnetic susceptibility and Kondo-like behavior in the electrical resistivity at high temperatures. Furthermore, non-Fermi liquid behavior is observed in the specific heat and electrical resistivity at low temperatures. NdRu₄Sb₁₂ and EuRu₄Sb₁₂ show a magnetic transition at 1.3 K and 3.3 K, respectively.