Comparison of Flux Pinning in Single Crystals and Melt-Textured YBa2Cu3O7-x
R. Puźniak1, A. Wiśniewski1, M. Baran1 and L. Zhou2

1 Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland
2Northwest Institute for Nonferrous Metal Research, Xi'an, P.R. China
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Flux pinning properties of single crystals and melt-textured samples of YBa2Cu3O7-x were studied for external magnetic field oriented parallel and perpendicular to the CuO2 planes (ab-planes). For H ∥ ab vortex behaviour is mainly determined by a very effective intrinsic pinning mechanism. The irreversibility line is located in the region of higher fields and temperatures in comparison with the irreversibility line for H ⊥ ab. In a single crystal for H ⊥ ab, we observed an increase in the critical current density jc with magnetic field - the so-called "fishtail effect" - in a very broad temperature range. For H ∥ ab, this effect is observed only at temperatures close to Tc, when the intrinsic pinning is much weaker.
DOI: 10.12693/APhysPolA.97.373
PACS numbers: 74.60.Ge, 74.60.Jg, 74.72.Bk