1 200 MeV Ag +15 ion irradiation created columnar defects and enhanced critical current density of La-2125 type superconducting thin films K. R. Mavani, a,b) D. S. Rana, a) S. Rayaprol, R. N. Parmar, D. G. Kuberkar Department of Physics, Saurashtra University, Rajkot – 360005, Gujarat, India Ravi Kumar Materials Science Division, Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi – 110067, India M. Tonouchi Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871, Japan J. John and R. Nagarajan Dept. of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Colaba, Mumbai-400005, India Abstract We have deposited c-axis oriented thin films of La 1.5 Dy 0.5 CaBa 2 Cu 5 O z (La-2125) tetragonal superconductor on LaAlO 3 (001) by Pulsed Laser Deposition. These films were irradiated with 200 MeV Ag +15 ions. Atomic Force Microscopy and Elastic Recoil Detection Analysis indicate that the irradiation has created columnar defects along the entire thickness (2000 Å) of these films. With ion irradiation up to 1×10 11 ions/cm 2 , the critical current density (J c (H)) is found to enhance by almost five folds, which is attributed to the augmented flux pinning by the columnar defects. A further increase in irradiation to 1×10 12 ions/cm 2 causes reduction in J c (H) due to distorted morphology of the film. Our work shows that the enhancement in J c (H) of the irradiated La-2125 film is comparable to that in irradiated RE-123. Also, as the La-2125 type films have greater chemical stability than RE-123 (RE = rare earth ion), La-2125 type superconductors are potential candidates for applications. Interesting to note that there are partial flux jumps observed to occur symmetrically in the magnetic hysteresis of irradiated La-2125 thin films with enhanced J c (H). a) Present address: Institute of Laser Engineering, Osaka University, Osaka, Japan. b) Email: mavani-k@ile.osaka-u.ac.jp, krushna1@gmail.com