ENERGY-GAP, TC, AND DENSITY OF STATES IN HIGH-TEMPERATURE SUPERCONDUCTORS FOR RETARDED S-WAVE AND D-WAVE INTERACTIONS

We employ strong-coupling theory to investigate the effect of the form of the spectral function 2F for isotropic and anisotropic interactions on the tunneling density of states N(), Tc, and the ratio 2/kBTc. Resistivity data are used to fix the isotropic coupling constant 01. This severely restricts the results for s-wave pairing; high-energy spectral weight is required in addition to phonons. The anisotropic interaction is not restricted by the resistivity and thus with d-wave pairing a variety of data, including the linear behavior of N() within the gap, can be fitted without high-energy interactions. © 1990 The American Physical Society.