Effect of boron, carbon stoichiometry on the superconducting properties of LuNiBxCy system

Superconducting properties of LuNiBxCy (0.8 ⩽ x, y ⩽ 1.2) have been investigated. Specific heat anomaly at Tc ∼ 2.6 K observed for the compound LuNiB0.9C, confirms the bulk superconductivity in the system. The N(Ef) value of 2.4 states/eV unit cell calculated from the specific heat measurements for the compound, is comparable with the theoretical value of 1.95 states/eV unit cell for the system. A highest Tc of 3.2 K has been achieved in the compound LuNiB0.8C1.2. Our results indicate that the variation of B and C stoichiometry has appreciable influence on the 1 1 1 1-type (LuNiBC) phase formation and its superconducting properties revealing the complex band structure dependence of the system.