Enhancement of critical current density of YBCO films by introduction of artificial pinning centers due to the distributed nano-scaled Y2O3 islands on substrates

We introduced high-density extended crystalline defects, which result in artificial pinning centers of the quantized vortices, into c-axis oriented YBa2Cu3O7-x, (YBCO) films. The crystalline defects created perpendicular to the film surface were derived, during the film deposition process, by the distributed nano-sized Y2O3 islands prepared on SrTiO3 (1 0 0) substrates. The Y2O3 nano-islands were approximately 3 urn in height and 25 nm in diameter and the density was controlled from about 89 to 212 mum(-2) by choosing the Y2O3 deposition condition. J(c)s of YBCO films grown on SrTiO3 substrates with the extended defects were increased by about 150% higher than those of YBCO films without the defects. (C) 2004 Elsevier B.V. All rights reserved.