Effect of mixed pinning landscapes produced by 6 MeV oxygen irradiation on the resulting critical current densities Jc in 1.3 µm thick GdBa 2 Cu 3 O 7- d coated conductors grown by co-evaporation

Abstract

We report the influence of crystalline defects introduced by 6 MeV 16

Competition between pinning produced by extrinsic random point disorder and superconducting thermal fluctuations in oxygen-deficient GdBa2Cu3O x coated conductors

“…In the framework of the collective creep theory, μ evolves from predictors for small (3/2) to large vortex bundles (7/9) as T c reduces. Unlike clean systems such as single crystals, the vortex pinning in the films is produced by a combination of a low density of nanoparticles, island boundaries and random disorder [17,25]. However, in analogy with columnar defects, if the number of vortices exceeds the number of nanoparticles, then the vortex dynamics be dominated by interstitial vortices trapped between the nanoparticles by the random disorder [26].…”

“…The objective of the present manuscript is to find a correlation between the vortex dynamics and J c values in thin films in which T c is suppressed by changes in the oxygen content and by disorder introduced by irradiation [9,13]. The pinning landscape in unirradiated films is produced mainly by Gd 2 O 3 inclusions with a typical size of≈50 nm [17]. We study the persistent current density J c and its decay with time from magnetic hysteresis measurements and relaxation studies, respectively.…”

Механизм Формирования Критического Тока Высокотемпературных Сверхпроводников, Содержащих Сквозные Микроскопические Дефекты

“…Наиболее распространенным способом повышения критического тока является создание искусственных центров пиннинга, препятствующих движению магнитного потока в сверхпроводнике, приводящего к появлению напряжения. Традиционными способами искусственного усиления пиннинга являются введение наноразмерных добавок (см., например, недавнюю работу по увеличению критического тока в ВТСП лентах второго поколения [1] и ссылки в ней), а также создание радиационных дефектов путем облучения ВТСП ионами высоких энергий, нейтронами и ударным плазменным воздействием [2][3][4][5][6][7][8][9]. При этом в сверхпроводящем материале формируются дефекты с характерным размером порядка длины когерентности, которые могут являться эффективными центрами пиннинга.…”

In-field dependences of the critical current density J in GdBa2Cu3O7-d coated conductors produced by Zr irradiation and post-annealing at low temperatures

“…Artificially designed mixed pinning landscapes seem to be a tool to improve critical current densities J c in high temperature superconductors [1,2,3]. A significant enhancement of the infield J c of RBa 2 Cu 3 O 7−δ (RBCO; R: Sm, Dy, Y, Gd) coated superconductors (CCs) can be obtained by adding pinning centers by ion irradiation [4,5,6,7,8]. For adequate irradiation fluences (which depend on mass and energy of ions), adding small clusters and random disorder assists the pinning produced by normal inclusions and twin boundaries (originated during the synthesis) [9,10].…”

“…The objective of this study is to find a correlation among the disorder produced by irradiation, the T c and the self-field and in-field dependence of J c . The pristine films display a pinning landscape with sphere-like and irregular precipitates (Gd 2 O 3 ) embedded in the GBCO matrix with typical diameter of approximately 50 nm [7]. In addition, correlated pinning produced by twin boundaries and boundaries between islands usually assists the pinning produced by the nanoparticles [13].…”