Effect of Proton Irradiation on the Critical Current in Tl₂Ca₂BaCu₂O₈ Bicrystal Josephson Junctions

Abstract

Josephson junctions made by depositing Tl₂Ba₂CaCu₂O₈ (T1-2212) high-temperature supeconducting films on a SrTiO₃ bicrystal were irradiated at room temperature with 2-MeV protons. Changes in the critical currentI _c and the temperatureT* at whichI _c approaches zero are reported as functions of the proton fluence. Following an initial drop at low fluences. similar to a pretreatment stage.I _c becomes significantly more resistant to radiation damage. At low fluences, the sensitivity ofI _c to radiation damage is apparently dominated by the presence of grains or bridges at the junction. At high fluences the dominant effect appears to be radiation-induced decreases in the transition temperatureT _c of the banks.