Superconducting and Magnetic Properties of Filled Skutterudite Compounds RERu_<b>4</b>Sb_<b>12</b>(RE=La, Ce, Pr, Nd and Eu)

Abstract

We have studied superconducting and magnetic properties of RERu 4 Sb 12 prepared by an Sb-flux method and found that LaRu 4 Sb 12 is superconducting below 3.58 K and PrRu 4 Sb 12 is a Van Vleck paramagnet which becomes superconducting below 1.04 K. CeRu 4 Sb 12 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. NdRu 4 Sb 12 and EuRu 4 Sb 12 show a magnetic transition at 1.3 K and 3.3 K, respectively.