Theoretical study on the superfluid density of the superconducting MNCl (M=Hf, Zr)

We consider the possibility of spin fluctuation mediated d+id′‐waved+id′‐wave pairing for the layered nitride superconductor MMCl. Using the superconducting gap obtained within the fluctuation exchange method for the two band model, we calculate the superfluid density as a function of temperature for several doping concentrations. Reflecting the fact that the anisotropy of the d+id′‐waved+id′‐wave gap on the Fermi surface is enhanced with the increase of the doping concentration, the overall doping dependence of the superfluid density is in qualitative agreement with the experiment.