PENETRATION DEPTH FOR A 2D D-WAVE SUPERCONDUCTOR

We have calculated the temperature dependence of the London penetration depth for a planar D-wave model superconductor with a simple tight binding band within the CuO plane. No Fermi surface approximation is introduced and a complete numerical integration over the Brillouin zone is carried out at fixed chemical potential. Impurity scattering in the Born and in the unitary limit are considered. A large amount of Born scattering is needed to change the low temperature dependence from a T to a T2 law while unitary scattering show this effect at the lowest concentrations considered.