The effect of 200MeV Ag ion irradiation on the superconducting and normal state properties of the high-Tc superconductor YBa2Cu3O7-y (YBCO) was studied by in situ temperature-dependent resistance measurements. It was shown that irradiating YBCO thin films (~150nm) at low temperatures resulted in a softly defective region of about 85nm radius due to swift heavy ion-induced secondary electrons around the highly amorphized latent tracks of ~5nm radius. This led to a decrease in Tc at fluences which were 3 orders of magnitude less than the threshold fluence, where overlapping of tracks blocked the super-current path. Due to their low energy (4.1keV for 200MeV Ag ions), the secondary electrons could induce point defects by inelastic processes rather than by direct elastic collision.

Point Defect Creation by Low Fluence Swift Heavy Ion Irradiation-Induced Low Energy Electrons in YBa2Cu3O7-y. R.Biswal, J.John, D.Behera, P.Mallick, S.Kumar, D.Kanjilal, T.Mohanty, P.Raychaudhuri, N.C.Mishra: Superconductor Science and Technology, 2008, 21[8], 085016 (6pp)