Publication: High pinning performance of YBa2Cu3O7-x films added with Y2O3 nanoparticulate defects
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Date
2015
Authors
Mele P.
Guzman R.
Gazquez J.
Puig T.
Obradors X.
Saini S.
Yoshida Y.
Mukaida M.
Ichinose A.
Matsumoto K.
Journal Title
Journal ISSN
Volume Title
Publisher
Institute of Physics Publishing
Abstract
We report the epitaxial growth and superconducting properties of Y2O3-added YBa2Cu3Ox (YBCO) films grown on SrTiO3-buffered MgO substrates by pulsed-laser deposition using surface-modified YBCO targets. Areas of Y2O3 sectors on the YBCO target were increased to 5.44% and 9.22% of the total YBCO pellet in order to find a correlation between the Y2O3 content, morphology, and the pinning properties of YBCO+Y2O3 mixed films. The maximum global pinning forces, FP, at 77 K were 14.3 GN m-3 and 1.15 GN m-3 for the Y2O3 5.44A% and 9.22A%, respectively. The 5.44A% Y2O3-added sample presents a very high value of pinning force at 77 K, approaching the value obtained in YBCO films with added BaZrO3 nanorods, but with less depression in the superconducting critical temperature, Tc. In accordance with scanning transmission electron microscopy (STEM) observations, both films present nanoparticulate Y2O3 dispersed in a YBCO matrix where Y2Ba4Cu8O16 (Y248) intergrowths were also observed. Consistent with the strong pinning theory, the size and distribution of randomly dispersed Y2O3 particles are optimal for the flux pinning of a 5.44A% Y2O3-YBCO film, while in the case of a 9.22A% film, the YBCO matrix is degraded by jam-packed Y248 intergrowth, which leads to a comparatively poor pinning performance. We further used the single-vortex dynamics model to account for vortex pinning in the samples. The 5.44A% Y2O3-YBCO film result shows good agreement with the model fit up to 4 T of the applied magnetic field. � 2015 IOP Publishing Ltd.
Description
Barium zirconate; Epitaxial growth; Flux pinning; High resolution transmission electron microscopy; Magnesia; Nanorods; Pulsed laser deposition; Scanning electron microscopy; Strontium titanates; Superconducting films; Titanium compounds; Transmission electron microscopy; Vortex flow; Yttrium barium copper oxides; Applied magnetic fields; Artificial pinning centers; isotropic pinning; Scanning transmission electron microscopy; Single vortices; Superconducting critical temperatures; Superconducting properties; YBCO film; Copper compounds