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Effects of Nanoscale Defects on Critical Current Density of (Y1-xEux)Ba2Cu3O7-delta Thin Films (Postprint)
AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIR/POWER DIV/MECHANICAL ENERGY CONVERSION BRANCH
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In pulsed laser deposition of YBa2Cu3O7-delta films, defect introduction into the films tends to anisotropically improve the pinning along the Hc direction due to the columnar growth mode of the process. In Eu-substituted samples, however, even though an increase in critical current density Jc in the Hc direction was observed for low fields H 0.2 T, the improvement was more notable for the Hab-plane at both low and higher fields. Herein we present detailed TEM microstructural studies to understand these new trends in JcH, which are markedly different than flux pinning increases achieved with other methods, for example, with nanoparticle additions. Threading dislocations, observed in the Eu-substituted samples along the c-axis, account for Jc enhancement with Hc at low field. The enhanced ab-planar pinning in the Eu-substituted samples is attributed to the extensive bending of the 0 0 1 lattice planes throughout the film, and the crystal lattice defects with excess Cu-O planes, that were effective in increasing the Jc for Hab at both low and high fields.
APPROVED FOR PUBLIC RELEASE