"Internal" coherent effects in HTS-normal metal point contacts

Abstract

Electrical characteristics are measured in submicron YBaCuO-normal metal point contacts with a direct conductivity. In a microwave field, such contacts reveal a nonstationary Josephson effect which can occur in the current concentration region not only in the initial weak bonds in YBaCuO but also the weak bonds of a phase-slip center type, formed as a result of a significant current injection (as well as a microwave field). The existence of internal weak bonds in the HTS-electrode contact area produces a narrow minimum in the differential resistance near zero biases. Moreover, the effect of magnetic flux quantization is observed for separate granules in magnetic fields stronger than the first critical field.