The effect of Ni doping on the electronic structure and superconductivity in the noncentrosymmetric ThCoC2

ThCoC2 is a non-BCS, noncentrosymmetric superconductor with Tc≃2.5 K, in which pairing mechanism was suggested to be either spin fluctuations or the electron–phonon coupling. Earlier experimental work revealed that Tc can be greatly enhanced upon Ni doping in ThCo1−xNixC2, up to 12 K for x=0.4. In this work, using the Korringa–Kohn–Rostoker method with the coherent potential approximation (KKR-CPA), the evolution of the electronic structure upon Ni doping was studied and the increase of the density of states at the Fermi level was found. The electron–phonon coupling constant λ was calculated using the rigid muffin tin approximation (RMTA) and the increase in λ(x) was found. This indirectly confirms the electron–phonon coupling scenario as the trend in λ(x) is in qualitative agreement with the experiment when the electron–phonon pairing is assumed.