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

We consider the possibility of spin fluctuation mediated d+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'-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. (C) 2010 Elsevier Ltd. All rights reserved.