Effects of artificial pinning centers on vortex pinning in high-temperature superconducting films

One-dimensional artificial pinning centers (APCs) were introduced perpendicular to the surface of the c-axis oriented YBa2Cu3O7−δ (YBCO) films by using Y2O3 nano-islands which were distributed on the substrates. In-field Jc of the films was remarkably enhanced by this method and reached to 0.12 MA/cm2 (77 K, B∥c, 5 T), which was 2-2.5 times higher than that of a pure YBCO film. The present films had a large Jc peak when the field was applied close to the c-axis. The results indicate that the strong APCs were introduced into the YBCO films. The vortex pinning by the present APCs is discussed based on the accommodation angle of the vortices.