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The role of a-axis grains in the transition to the normal state of YBa2Cu3O7−δ films and of 2G-coated conductors when induced by high electrical current densities

Bernstein, Pierre and Ferro, Gabriel and Harnois, Christelle and Mc Loughlin, Conor and Noudem, Jacques G. and Osorio, Maria Rosa and Thimont, Yohann and Veira, Juan A. and Vidal, D and Vidal, F. The role of a-axis grains in the transition to the normal state of YBa2Cu3O7−δ films and of 2G-coated conductors when induced by high electrical current densities. (2014) Journal of Applied Physics, 115 (5). 1-11. ISSN 0021-8979

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Official URL: https://doi.org/10.1063/1.4864713

Abstract

The influence of surface defects, in particular of a-axis grains, on the transition to the normal state induced by high current densities in YBa2Cu3O7−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.

Item Type:Article
HAL Id:hal-02057550
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Other partners > Ecole Nationale Supérieure d'Ingénieurs de Caen - ENSICAEN (FRANCE)
Other partners > Universidad de Santiago de Compostela - USC (SPAIN)
Other partners > Université de Caen Basse-Normandie (FRANCE)
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Deposited On:05 Mar 2019 13:04

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