Flux Pinning Properties of Bi,Pb2223 Films With Columnar Defects by Xe Irradiation

High-quality Hf- and Zr-doped Bi,Pb2223 films on SrTiO3 substrate were fabricated by RF magnetron sputtering and two-step annealing. In order to investigate flux pinning properties of columnar defects, Xe-ions were irradiated onto the Hf- and Zr-doped Bi,Pb2223 films along the c-axis. Although the critical temperature T-c was decreased by heavy ions irradiation, the infield critical current density J(c) in the magnetic field parallel to the caxis was increased drastically. The enhancement of J(c) was achieved in a wide range of magnetic fields over the matching magnetic field B-phi. In the angular dependence of J(c), the improvement of J(c) was observed in almost all angle region of magnetic field orientation except for the vicinity of the ab-plane. However, the peak centered at the c-axis did not appear in the angular dependence of J(c). This behavior was quite different from REBa2Cu3Oy films installed columnar defects. The angular dependences of J(c) in the Hf- and Zr-doped Bi,Pb2223 films were determined by the magnetic field component along the c-axis. These results are originated from the strong two-dimensional nature of the Bi,Pb2223 film.