C-AXIS SUPERFLUID RESPONSE OF COPPER-OXIDE SUPERCONDUCTORS

A novel interplay between d-wave superconducting order parameter symme try and the underlying Cu 3d orbital based electronic structure of cop per oxides leads to a striking anisotropy in the superfluid response o f these systems. In clean tetragonal materials the c axis penetration depth increases as T-5 at low temperature, in contrast to linear T beh avior in the ab plane. Disorder is a relevant perturbation which cause s all components of the superfluid response to depend quadratically on temperature at low temperature. However, the crossover temperature sc ale from the intrinsic d-wave behavior to the disorder dominated behav ior for the in-plane response may be different from that for the out-p lane response.