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Weak emergence in the angular dependence of the critical current density of the high temperature superconductor coated conductor REBCO

Branch, Paul; Osamura, Kozo; Hampshire, Damian

Weak emergence in the angular dependence of the critical current density of the high temperature superconductor coated conductor REBCO Thumbnail


Authors

Paul Branch

Kozo Osamura



Abstract

Extensive critical current density Jc measurements are reported as a function of magnetic field B, temperature T, angle θ between the applied field and the surface of the tape, and strain ε, on a REBCO coated conductor. The strain, εpeak (B,T, θ), at which Jc (εapp) is maximised, is a function of B, T, and θ, which is consistent with weakly emergent behaviour. It is described by the chain model that considers competition between twinned domains with different crystallographic orientations and opposing responses under an applied uniaxial strain. Detailed effective upper critical field B ∗ c2 (T, εapp,θ = 0) data are presented that show universal temperature and strain scaling. They lead to an accurate flux pinning relation for the volume pinning force, Fp ∝ Fp,maxb p (1 − b) q , where b = B/B ∗ c2 (T, εapp,θ = 0) and p and q are constants, and are used to help parameterise the scaling behaviour of the angular Jc data more accurately in those cases where B ∗ c2 cannot be measured directly. We derive approximate analytic in-field expressions that explain how the fraction, f, of a-domains amongst the a- and b-domains affects the strain dependence of the critical parameters and conclude that in our tape, f = 0.4, and the strain at which Jc is the same in both domains is εJcA=JcB = 0.15%. We report a sharp peak in Jc as the applied field approaches alignment with the ab-plane and the unusual result that with it, a suppression of the index of transition N also occurs. We find that the effective upper critical field B * c2 increases as the field angle approaches the ab-plane significantly faster than any available theoretical model for the upper critical field Bc2. In addition, we conclude that a weak-emergence description is not limited to high temperature superconductors, but also describes some low-temperature superconductors.

Citation

Branch, P., Osamura, K., & Hampshire, D. (2020). Weak emergence in the angular dependence of the critical current density of the high temperature superconductor coated conductor REBCO. Superconductor Science and Technology, 33(10), Article 104006. https://doi.org/10.1088/1361-6668/abaebe

Journal Article Type Article
Acceptance Date Aug 12, 2020
Online Publication Date Sep 3, 2020
Publication Date 2020-10
Deposit Date Oct 7, 2020
Publicly Available Date Mar 29, 2024
Journal Superconductor Science and Technology
Print ISSN 0953-2048
Electronic ISSN 1361-6668
Publisher IOP Publishing
Peer Reviewed Peer Reviewed
Volume 33
Issue 10
Article Number 104006
DOI https://doi.org/10.1088/1361-6668/abaebe

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http://creativecommons.org/licenses/by/4.0/

Copyright Statement
Original content from this work may be used under the terms
of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.





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