Critical current density enhancement by ion irradiation for thick YBa2Cu3O7−δ films prepared by diffusion reaction technique

In the present work we have investigated the effect of 200 MeV Ag ions on YBa2Cu3O7−δ/Y2O3 (5 wt.% and 10 wt.%) composite thick films. The samples were characterized using temperature dependent resistivity and magnetization measurements. The residual resistivity, mean field transition temperature and the zero resistance state are appreciably modified due to swift heavy ion irradiation (SHI). With the increase in defect density for 10 wt.% Y2O3 added samples irradiated with Φ ⩾ 5 × 1011 ions/cm2 shows semiconducting behavior above the transition temperature marked by broadening of transition width. Pseudogap temperature regime estimated from the deviation of linear behaviour from resistivity data indicates a shift to lower temperature zone. Synergetic effect of SHI and Y2O3 show enhancement of critical current density and flux pinning at 40 K for 5 wt.% Y2O3 inclusions. However, 10 wt.% Y2O3 added films after ion bombardment records lower values of critical current density and flux pinning. The results are explained on the basis of interplay of defect density and pinning of vortices in the YBCO matrix.