QUASI-PARTICLE TUNNELING OF D-WAVE SUPERCONDUCTORS

There are apparently contradicting evidence about the high-Tc supercon ducting order parameter symmetry from the experimental studies of Jose phson currents. Although there are far more experimental studies about the quasi-particle tunneling of high-Tc superconductors in various ge ometries, it is difficult to extract the nature of the order parameter because of lacking theoretical comparison. We calculate I-V curves an d dI/dV-V curves of quasi-particle tunneling from high-Tc superconduct or to normal metal. The normal state of the high-Tc superconductor is assumed to be that of a 2-D tight-binding model. Numerical results alo ng different crystalline directions for the d-wave symmetry are carrie d out. The differences in the conductance spectra are emphasized and c ompared with available experimental data.