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Title: The role of a-axis grains in the transition to the normal state of YBa{sub 2}Cu{sub 3}O{sub 7−δ} films and of 2G-coated conductors when induced by high electrical current densities

The influence of surface defects, in particular of a-axis grains, on the transition to the normal state induced by high current densities in YBa{sub 2}Cu{sub 3}O{sub 7−δ} (YBCO) thin films and in a commercial 2G-coated conductor is investigated. For that purpose, the surface of the samples is observed by scanning electron microscopy and isothermal current-voltage curves are measured at different temperatures with pulsed currents up to the quenching value I*. The results show that the ratio of I* to the critical current is large if a-axis grains are not visible at the surface of the YBCO films, while it is much lower if the surface includes a-axis grains as this is the case for the coated conductor. The connection between the transition onset and the vortex dynamics, as well as the role of the a-axis grains in this process are discussed. The relation between the I* values obtained from thermal calculations and those resulting from vortex dynamics considerations is also discussed, as well as the possible consequences suggested by this work for the different applications of the coated conductors.
Authors:
; ; ; ;  [1] ; ; ; ; ;  [2]
  1. CRISMAT-ENSICAEN (UMR CNRS 6508)–Université de Caen-Basse Normandie, Boulevard du Maréchal Juin, F14050 Caen cedex (France)
  2. LBTS, Departamento de Fisica da Materia Condensada, Universidade de Santiago de Compostela, Santiago de Compostela E15782 (Spain)
Publication Date:
OSTI Identifier:
22278104
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 5; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; BARIUM OXIDES; COPPER OXIDES; CRITICAL CURRENT; CUPRATES; CURRENT DENSITY; ELECTRIC CONDUCTIVITY; HIGH-TC SUPERCONDUCTORS; SCANNING ELECTRON MICROSCOPY; SURFACES; TEMPERATURE DEPENDENCE; THIN FILMS; VORTICES; YTTRIUM OXIDES