Conductance zero bias anomaly in high temperature superconducting grain boundary Josephson junctions

A zero-bias conductance peak is found in the tunneling characteristics of high temperature superconducting bicrystal grain boundary junctions (GBJs). The analysis of the anomaly is performed in terms of spin-flip and Kondo-type scattering at the interface (Anderson-Applebaum model). Applying a magnetic field parallel to the grain boundary barrier the splitting of the Kondo peak is observed implying the existence of spin-flip and Kondo-type scattering in the grain boundary barrier.