Friday, 2D-05, 3:50-4:00

Highly Tunable, Rare Earth Tantalate Pyrochlore Nanoparticles for Superior Flux Pinning in YBaCuO Films

S. A. Harrington

J. H. Durrell¹, B. Maiorov², H. Wang³, S. C. Wimbush¹, A. Kursumovic¹, J. H. Lee³, J. L. MacManus-Driscoll¹

¹Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ, UK
²Superconductivity Technology Centre, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
³Department of Electrical and Computer Engineering, Texas A&M University, College Station, Texas 77843, USA sah59@cam.ac.uk, +44 (01223) 33 43 75,

Practical flux pinning in the high temperature superconductor, YBaCuO (YBCO), was first demonstrated around five years ago. Since that time, significant progress has been made in materials optimisation and the various candidate pinning additives show several factors higher current carrying performance in magnetic field than standard YBCO. Despite the major advances, there has been little basic understanding about what is the optimum additive and how to achieve the 'perfect' pinning microstructure. Here, through a simple understanding of the kinetic and thermodynamic factors at play, combined with a knowledge of the materials chemistry of candidate pinning phases, we propose a new pinning additive, RE₃TaO₇ (where RE is rare earth). We demonstrate a very fine pinning nanostructure from the phase as well as exemplary flux pinning. The nanoparticle self-assembly is readily tunable, allowing for both strong random and correlated pinning. State-of the art or better pulsed laser deposition current densities, J_c's, of 1.2 MA.cm^-2 at 1 T, 0.55 MA.cm^-2 at 3 T, and 0.2 MA.cm^-2 at 5 T, were achieved in the first grown films.

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