Strongly enhanced vortex pinning from 4 to 77 K in magnetic fields up to 31 T in 15 mol.% Zr-added (Gd, Y)-Ba-Cu-O superconducting tapes

Abstract

Applications of REBCO coated conductors are now being developed for a very wide range of temperatures and magnetic fields and it is not yet clear whether vortex pinning strategies aimed for high temperature, low field operation are equally valid at lower temperatures and higher fields. A detailed characterization of the superconducting properties of a 15 mol. % Zr-added REBCO thin film made by metal organic chemical vapor deposition, from 4.2 to 77 K under magnetic fields up to 31 T is presented in this article. Even at a such high level of Zr addition, Tc depression has been avoided (Tc = 91 K), while at the same time an exceptionally high irreversibility field Hirr ≈ 14.8 T at 77 K and a remarkably high vortex pinning force density Fp ≈ 1.7 TN/m3 at 4.2 K have been achieved. We ascribe the excellent pinning performance at high temperatures to the high density (equivalent vortex matching field ∼7 T) of self-assembled BZO nanorods, while the low temperature pinning force is enhanced by large additional pinning which we ascribe to strain-induced point defects induced in the REBCO matrix by the BZO nanorods. Our results suggest even more room for further performance enhancement of commercial REBCO coated conductors and point the way to REBCO coil applications at liquid nitrogen temperatures since the critical current density Jc(H//c) characteristic at 77 K are now almost identical to those of fully optimized Nb-Ti at 4 K.

Measurement and Numerical Evaluation of AC Losses in a ReBCO Roebel Cable at 4.5 K

“…It is expected that the engineering current density of the tapes will still increase significantly. On short lengths very high current densities have already been achieved using Zr doping [11], [12]. When such conductors become available in longer lengths one can imagine an efficient, low cross sectional area, very high field magnet.…”

Tuning nanoparticle size for enhanced functionality in perovskite thin films deposited by metal organic deposition

“…3,16 Moreover, recent work has shown that large quantities (⩾10%) of second-phase additions are required to obtain the desired level of performance in superconductors. [17][18][19] Until now, such a large amount of second phase resulted in current blocking and the loss of crystallinity. 19,20 For REBCO superconductors, MOD has been shown to be amenable for growing extremely high performance materials [21][22][23][24][25][26] with high throughput; [27][28][29] however, the tailoring of NP inclusions is extremely difficult.…”

Impact of pseudo-gap states on the pinning energy and irreversibility field of high temperature superconductors

“…This has turned out to be a highly non-trivial requirement, although great advances have been made recently in this direction. [1][2][3][4] It was discovered empirically that vortex pinning was in general much weaker in the HTS than in low temperature superconductors. It is well understood that the very short coherence length plays an important role in this difference.…”

“…2 In addition to the strain effect, we believe that overdoping may also contribute to the record values of the irreversibility field recently reported for YBCO films including BZO inclusions. [1][2][3] A theory that explains how strain can induce vortex pinning can be based on the Bond Contraction Pairing (BCP) model. 18 This model predicts that a contraction of the order of 1% of Cu-O bonds is sufficient to induce pair localization.…”