IMPURITIES AND INTERFACE SCATTERING EFFECT ON THE DIFFERENTIAL CONDUCTANCE NORMAL METAL-d-WAVE SUPERCONDUCTOR JUNCTIONS

Taking into account the impurities and rough interface scattering, using Bogoliubov-de Gennes (BdG) equations and Bolonedr-Tinkham-Klapwijk (BTK) model, we calculate the differential conductance of normal metal-d-wave superconductor. It is found that the tunneling spectum depends strongly on both the incident angle electrons and the crystalline axis orientation of superconductor, and exhibits the zero-bias conductance peak under suitable arrangements. Morevover, the zero-bias conductance dip can be splitted into two small conductance dips by the impurities scattering, the tunnel conductance peak at the energy gap and the zero-bias conductance are suppressed and smoothed by the interface roughnes. Our result can explain many experimental measurements on the tunneling spectum of high-Tc superconductors.