Three-dimensional vortex pinning by nano-precipitates in a Sm-doped YBa2Cu3O7−xcoated conductor
| Autor: | Venkat Selvamanickam, Xueyan Song, Z Chen, Y Y. Xie, Alex Gurevich, Sang-Il Kim, David C. Larbalestier, Jodi L. Reeves, D.M. Feldmann |
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| Rok vydání: | 2007 |
| Předmět: | |
| Zdroj: | Superconductor Science and Technology. 20:S205-S210 |
| ISSN: | 1361-6668 0953-2048 |
| DOI: | 10.1088/0953-2048/20/9/s14 |
| Popis: | We report on the thickness and angular dependence of the critical current density Jc(H,?), the irreversibility field Hirr, and the bulk pinning force Fp(H) of a metal-organic chemical vapour deposition (MOCVD) grown YBa2Cu3O7?x (YBCO) coated conductor, which contains ~17?vol% of ~10?nm sized (Y,Sm)2O3 precipitates with an average spacing of ~10?15?nm. Some surface porosity and amorphous second-phase particles on the scale of ~0.5?1??m appear to reduce the current-carrying cross-section, which controls the magnitude of Jc but not the vortex pinning. We observed an enhanced Hirr~9? T at 77?K along the c-axis which, like the shape of Jc(H) and Fp(H), was independent of thickness as the sample was milled down to ~0.16??m. Angular-dependent measurements of Jc showed the usual excess vortex pinning along the c-axis and along the ab-plane, but with a background that could only be fitted with an unusually small anisotropy parameter of 3, which, like the high Hirr and the thickness-independent shape of Fp(H), we ascribe to strong vortex pinning centre interactions. Together, these measurements show very different behaviour from most pulsed-laser-deposited films, which exhibit strong thickness-dependent properties. We ascribe the present different results to the dense array of small, insulating precipitates, which act as strong pinning centres and produce strong three-dimensional (3D) vortex pinning, because their separation of 10?15?nm is always much smaller than the film thickness. |
| Databáze: | OpenAIRE |
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