Tuning of superconductivity by Ni substitution into noncentrosymmetric ThCo1-xNixC2

The recently discovered noncentrosymmetric superconductor ThCoC2 was observed to show unusual superconducting behavior with a critical temperature of T-c = 2.65 K. Here we investigate the effect of nickel substitution on the superconducting state in ThCo1-x NixC2. Magnetization, resistivity, and heat capacity measurements demonstrate Ni substitution has a dramatic effect with critical temperature increased up to T-c = 12.1 K for x = 0.4 Ni concentration, which is a rather high transition temperature for a noncentrosymmetric superconductor. In addition, the unusual superconducting characteristics observed in pure ThCoC2 appear to be suppressed or tuned with Ni substitution towards a more conventional fully gapped superconductor.