INTERPLAY BETWEEN BAND-STRUCTURE AND GAP SYMMETRY IN A 2-DIMENSIONAL ANISOTROPIC SUPERCONDUCTOR

We consider the two-dimensional quasiparticle density of states and superconductor-insulator-superconductor (SIS) tunneling conductance, sigma(V), using a BCS-like framework for a gap function exhibiting the symmetries of an unspecified off-site pairing interaction. For d-wave pairing, we find the usual nodal structure in the gap function. In addition, one can also find nodal structure at the Fermi surface for a gap function with extended s-wave symmetry (but only when hopping beyond near neighbors is considered). This is a universal feature arising solely due to the interplay between the Fermi-surface geometry and the momentum variation of the gap function and leads to unique signatures in the SIS tunneling spectra.