Zero-bias anomalies in high-Tc-superconductor tunnel junctions

The zero-bias conductance peak that is often found in the tunneling characteristics of high-temperature-superconductor (HTS) junctions is analyzed in the framework of the Anderson-Appelbaum model for electron magnetic interaction. We have found that when the anomaly develops at T>${\mathit{T}}_{\mathit{c}}$, its temperature behavior is determined by the superconducting properties of the HTS, while, when it develops at T<${\mathit{T}}_{\mathit{c}}$, the presence of normal or semiconducting surface regions can be supposed. A giant resistance peak seems to indicate interdiffusion of the counterelectrode into the base material.