Point Defect Creation by Swift Heavy Ion Irradiation Induced Low Energy Electrons in YBa2Cu3O7-y

Abstract

The effect of 200 MeV ion irradiation on the superconducting and normal state properties of the high-Tc superconductor (YBCO) is studied by in-situ temperature dependent resistance measurement. We show that irradiating YBCO thin films (~150 nm) at low temperature result into a softly defected region of about 85 nm radius due to swift heavy ion induced secondary electrons around the highly amorphized latent tracks of ~ 5 nm radius. This leads to decrease of Tc at fluences three orders of magnitude less than the threshold fluence, where overlapping of tracks block supercurrent path. Due to their low energy (4.1 keV for 200 MeV ion), the secondary electrons can induce point defects by inelastic process rather than by direct elastic collision