Superconducting-state properties and electronic band structure calculations of a noncentrosymmetric Th7Ni3 compound

Superconducting-state properties of a noncentrosymmetric Th7Ni3 compound have been investigated using magnetic, electrical resistivity and specific heat measurements as well as by electronic band structure calculations. The study reveals that the studied compound is a dirty type-II superconductor with K and a weak electron-phonon coupling . Moreover, in contrast to an exotic superconductivity observed previously in Th7Fe3 and Th7Co3, data reported in this paper give clear evidence that Th7Ni3 is a conventional single-gap superconductor. The experimental results are supported by DFT calculations of the electronic band structure, density of states, electron localization functions and Fermi surfaces which were performed using the full-potential linear muffin-tin-orbital and full-potential linearized augmented plane wave methods. Theoretical data show that asymmetric spin-orbit coupling in Th7Ni3 is quite small; hence the electronic band structure of this compound is weakly affected by the spin-orbit effects. We have determined fundamental parameters of Th7Ni3 and compared the superconducting properties with other Th7T3 (T = Fe, Co and Ru) compounds.