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ST174 - Effect of Nanosize BaZrO3 Inclusions on Vortex Parameters in YBa2Cu3O7−x

Effect of Nanosize BaZrO3 Inclusions on Vortex Parameters in YBa2Cu3O7−x

E. Silva1, N. Pompeo2, R. Rogai2, A. Augieri3, V. Galluzzi3, G. Celentano3

1Dipartimento di Fisica “E. Amaldi” and Unità CNISM, Università Roma Tre,
and INFM-CNR “SUPERMAT”, Via della Vasca Navale 84,
00146 Roma, Italy
2Dipartimento di Fisica “E. Amaldi” and Unità CNISM, Università Roma Tre,
Via della Vasca Navale 84, 00146 Roma, Italy
3ENEA-Frascati, Via Enrico Fermi 45, 00044 Frascati, Roma, Italy

E-mail: [email protected]

ABSTRACT - We report on the field dependence of the microwave complex resistivity data in YBa2Cu3O7−x/BaZrO3 films grown by PLD at various BaZrO3 content. The data, analyzed within a recently developed general framework for the mixed-state microwave response of superconductors, yield the field dependence of the fluxon parameters such as the vortex viscosity and the pinning constant. We find that pinning undergoes a change of regime when the BaZrO3 content in the target increases from 2.5 mol.% to 5 mol.%. Simultaneously, the vortex viscosity becomes an increasing function of the applied magnetic field. We propose a scenario in which flux lines are pinned as bundles, and a crossover from dilute point pins to dense c-axis correlated defects takes place between 2.5 and 5 mol.% in the BZO concentration. Our data are inconsistent with vortices occupying mainly the BaZrO3 sites at low fields, and suggest instead that vortices occupy both BaZrO3 sites and interstitials in the YBa2Cu3O7−x matrix, even at low fields.

IEEE/CSC & ESAS EUROPEAN SUPERCONDUCTIVITY NEWS FORUM (ESNF), No. 11, January 2010
Published in Journal of Physics Conf. Series (SuST234, 012040 (2010)