Suppression of Superconductivity in Thin-Film YBa₂Cu₃O_7-δ

The superconducting properties of YBaCuO thin-films were investigated by conducting 1.7 MeV proton irradiations. The experimental procedure was similar to the previous study (0.6 MeV proton irradiation). We compared the effectiveness of T_c suppression by varying the proton energy from 0.6 to 1.7 MeV and found that in general both protons of 1.7 MeV and 0.6 MeV were effective in suppressing the T_c of YBCO. For heavily irradiated cases (more than 80% T_c suppression), however, 1.7 MeV protons were more effective in suppressing T_c than 0.6 MeV protons. This can be understood by the fact that in thin-film samples, higher energy protons tend to produce less clustered point-defects while lower energy protons tend to create agglomeration of point-defects. This result increases our understanding of cuprate materials for use in electronic systems such as fusion reactors and space telecommunications high-frequency filters.