Energy-Dependent Effects of Proton Irradiation on the Superconducting Properties of Thin-Film TBCCO-2212

We investigated the effect of proton irradiation at 0.6 MeV and 1.7 MeV on the superconducting and normal-state properties of the thin-film TBCCO-2212 superconductor.  Two 650 nm thick samples were subjected to a series of proton irradiation totaling a fluence of 5.2 × 10¹⁶ p/cm² and 3 × 10¹⁷ p/cm².  As expected, the superconducting critical temperature (T_c) decreased from 100 K toward zero Kelvin, and the normal-state resistivity increased accordingly. By comparing the two energy ranges, we find a stronger rate of T_c suppression under 1.7 MeV irradiation, providing new insights into the energy dependence of irradiation-induced disorder in d-wave superconductors. From the result, the 1.7 MeV data was closer to the generalized d-wave AG theory curve than our previous experiment with 0.6 MeV proton irradiation.