Broad temperature range study of Jc and Hirr anisotropy in YBa2Cu3Ox thin films containing either Y2O3 nanoparticles or stacking faults

Industrially optimized coated conductors generate very high current densities J(c) and irreversibility field H-irr by quasi-empirical additions of multiple pin types. However, their microstructural complexity makes it hard to securely explain all aspects of their properties. We here describe the properties of two specially grown pulsed laser deposited YBa2Cu3Ox thin films with simpler pinning landscapes, for which we conducted detailed J(c)(T, H, theta) and Hirr(T, H, theta) characterizations from 10 K to T-c, and in magnetic fields up to 31 T. One film has a random insulating Y2O3 nanoparticle distribution, while the second was grown with many ab-plane stacking faults. As a whole, the Y2O3-containing sample shows significantly higher J(c)(theta) at all temperatures, except around the ab-plane at greater than 40 K. Consistent with our earlier studies of the effect of BaZrO3 (BZO) nanorods in commercial coated conductors, we find that there is significant additional J(c) at low temperatures when insulating precipitates with strain mismatch are present that we attribute to point defect pinning that can resist thermal fluctuations only below about 30 K. In addition to this significantly enhanced low temperature J(c), the Y2O3-containing thin film also exhibits significantly reduced effective Ginzburg-Landau (G-L) anisotropy parameter fits for H-irr(theta), which fall to gamma(eff) approximate to 3.6 from the more usual gamma(eff) approximate to 5 in the stacking-fault containing thin film. Of significant practical importance is our finding that the Y2O3 containing film achieved a bulk flux pinning force density F-p of 1000 GN/m(3) at 16 T and 4.2 K, a value about 30% larger than the mixed BZO-RE2O3 pin coated conductors which are presently the state of the art. (C) 2015 AIP Publishing LLC.