EFFECT OF PROTON IRRADIATION ON THE CRITICAL-CURRENT IN TL2CA2BACU2O8BICRYSTAL JOSEPHSON-JUNCTIONS

Josephson junctions made by depositing Tl2Ba2CaCu2O8 (T1-2212) high-te mperature superconducting films on a SrTiO3 bicrystal were irradiated at room temperature with 2-MeV protons Changes in the critical current I-c and the temperature T at which I-c approaches zero are reported as functions of the proton fluence. Following an initial drop at low f luences, similar to a pretreatment stage, I-c becomes significantly mo re resistant to radiation damage. low fluences, the sensitivity of I-c to radiation damage is apparently dominated by the presence of grains or bridges at the junction. At high fluences the dominant effect appe ars to be radiation-induced decreases in the transition temperature T- c of the banks.