On the macroscopic s- and d-wave symmetry in cuprate superconductors

The relevant recent experiments probing the surface and probing the bulk of cuprate superconductors are reviewed. The former yield without doubt d-wave symmetry, whereas the latter suggest a substantial s-symmetry component, at least. To reconcile these observations, it is proposed that the superconducting wavefunction varies as a function of the distance x from the surface. Its character is d on the surface and substantially s in the bulk. This is only possible by going beyond known classical solid-state theory, but it is borne out by the presence of supersymmetry.