Effect of proton irradiation on the properties of YBCO thin-film superconductors

We studied the effect of 600 keV proton irradiation on the properties of YBCO thin film superconductors. A 500 nm thick YBCO-1237 sample was subjected to a series of proton irradiations with a total fluence of 7.2 x 10¹⁶ p/cm². Upon irradiations, the superconducting critical temperature (T_c) was drastically decreased from 90 K towards zero Kelvin, and the normal state resistivity increased accordingly. The rate of T_c reduction to resistivity increase will be used to discuss the relation between impurity and superconducting gap.