Low-Temperature Thermodynamic Properties of Superconducting Antiperovskite CdCNi 3

Abstract

We investigate the thermodynamic parameters of the superconducting antiperovskite CdCNi3 using the Eliashberg approach which is an excellent tool to the exact characterization of the conventional superconductors. In particular, we reproduce the measured superconducting transition temperature (TC= 3.2 K) for a high value of the Coulomb pseudopotential (μC⋆=0.22). Then we determine the energy gap, the thermodynamic critical field and the specific heat for the superconducting and normal state. On this basis, we show that the thermodynamic properties of CdCNi3 differ slightly from the prediction of the Bardeen–Cooper–Schrieffer theory, which means that CdCNi3 is a medium-coupling superconductor in contrast to related strong-coupling MgCNi3.