Josephson tunneling in Bi2Sr2CaCu2O8+δ single-crystal break junctions

Abstract

Josephson tunneling I-V characteristics have been observed in break junctions of oxygen-annealed Bi2Sr2CaCu2O8 (Bi-2212) single crystals, with IcRn≈21.3 mV, and with a sharp quasiparticle edge at 2Δ≈2×20 mV. This demonstrates that low values of the IcRn product, thus far as observed in HTS thin-film junctions, do not represent a fundamental limitation. The sharp quasi-particle current rise at eV=2Δ in these SIS break junctions appears to afford an accurate measurement to be made of a well-defined gap edge.