Superconductivity in new quaternary borocarbide system R-Re-B-C (R=Y, Gd, Tb and Lu)

We report here our observation of superconductivity in a new quaternary borocarbide system R-Re-B-C (R=Y, Gd, Tb and Lu). Samples of the nominal compositions RReBC exhibit superconductivity with Tc ≈ 6 K in LuReBC which is high for an intermetallic. TbReBC and GdReBC exhibit superconductivity at ≈ 4 K. A magnetic transition is also observed in TbReBC around 30 K. From our measurements, we infer that superconductivity originates from a bulk quaternary superconducting phase in these materials