Critical current enhancement in PLD YBa2Cu3O7−x films using artificial pinning centers

Abstract

We introduced high-density columnar defects as artificial pinning centers (APCs) for quantized vortices into YBa2Cu3O7−x (YBCO) films during the film deposition procedure. APCs were introduced perpendicular to the film surface using nano-sized Y2O3 islands prepared on SrTiO3(100) substrates. Varying the deposition parameters and the substrate annealing conditions allowed strong changes in the shape and density of the Y2O3 islands to be induced. Compared to a pure YBCO film, the best performance among the APCs samples was obtained on the Y2O3-deposited substrate with 5 laser pulses, corresponding to a nominal thickness of 0.2nm. Even when the APC films were prepared using the same deposition conditions, the columnar defects enhanced Jc at 77K from 1.8 to 2.7MA/cm2 (self field) and from 0.06 to 0.10MA/cm2 (H=5T, H∥c-axis).