High critical current density and its field dependence in mixed rare earth (Nd,Eu,Gd)Ba2Cu3O7−δ thin films

Abstract

Compared with mono-rare earth 123 films, ternary rare earth (Nd,Eu,Gd)Ba2Cu3O7−δ (NEG123) films show higher critical current density (Jc) and improved irreversibility field (Hirr), but no increase in the characteristic field corresponding to a crossover from a low-field plateau to a linear region in a log Jc–log H plot. At intermediate fields, Jc vs H scales as H(−0.5±0.05) for NEG123, in contrast to H(−0.73±0.05) for mono-rare earth samples such as Gd123. The slow power decay of Jc vs H together with the improved Jc and Hirr strongly implies that extra flux pinning centers exist in NEG123, which are thought to be noncorrelated stress fields induced by lattice mismatch.

Epitaxial Growth of High-J c NdBa2Cu3O7−δ Films on RABiTS by Pulsed Laser Deposition

“…1 Likewise, REBCO films grown on single-crystal substrates have been reported to have better field dependence of J c than YBCO films. [3][4][5][6] Nevertheless, the difficulty in growing high-J c REBCO films has restricted a possibility for use in coated conductors. Recently, Takahashi et al reported that GdBa 2-Cu 3 O 7-d (GdBCO) films grown on IBAD-Gd 2 Zr 2 O 7 buffer layered metallic substrates had higher selffield J c at 77 K as well as better J c in applied magnetic fields than YBCO films.…”

Enhancement of flux pinning and critical currents in YBa2Cu3O7−δ films by nanoscale iridium pretreatment of substrate surfaces

“…5 Recently, a number of studies have reported the use of nanostructural manipulation to artifically introduce extra pinning sites into YBCO films for enhanced pinning. Examples include multilayering of YBCO with second-phase materials, 6,7 mixed rare-earth doping, 8,9 target compositional modifications either by second-phase BaZrO 3 inclusions 10 or creation of columnar defects comprised of self-aligned BaZrO 3 nanodots and nanorods, 11 process-induced modifications with excess yttrium, 12 and decoration of substrate surfaces by nanoscaled particles. 4,13,14 While all these methods have shown substantial improvements in the angular dependence and in-field J c performance of YBCO films, controlling the number density, morphology, and dimensions of the pinning structures in the superconducting matrix is not straightforward.…”

High critical current density and its magnetic fields dependence in (Sm,Eu,Gd)Ba2Cu3Oy films by using multiple targets

“…Irreversibility fields (B irr ) of the SEG123 film at 77 K were 12.1 T. 12.1 T is higher than that of typical Y123 and Sm123 films. Moreover, this value is higher than 11.8 T of LTG-NEG123 [9] and 9.2 T of PLD-NEG123 [10] films. Therefore, we infer that SEG123 films are effective materials for applications in high magnetic fields.…”