Spatially resolved observation of charge transfer across single grain boundaries in YBaCuO films

Transport properties of a single YBaCuO grain boundary have been investigated with a spatial resolution of 1 μm for voltages up to 70 meV. The conductance versus voltage characteristic is found to increase linearly for voltages between 6 and 40 mV. Below 2 mV this characteristic shows periodic oscillations. The origin of these features is discussed. © 1990.