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Low field anomaly in the critical current of Ba1−X Kx Fe2As2 tapes

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posted on 2024-11-28, 22:27 authored by Nicholas StricklandNicholas Strickland, Shen ChongShen Chong, C Dong, X Zhang, Y Ma, Zhenan JiangZhenan Jiang
Ba1−x K x Fe2As2 superconductors have strong potential for magnet applications through their very high upper critical field, relatively high superconducting transition temperature and manufacturability through the powder-in-tube (PIT) route. However, the critical current density in PIT tapes is still low compared to the incumbent technologies, so a greater understanding of the limiting factors is required. We have measured the in-field critical currents (I c) of stainless steel and silver double-sheathed monofilament Ba0.6K0.4Fe2As2 superconductor tapes at elevated temperatures from 15 K to 35 K. At 20 K, the critical current density is up to 140 kA cm−2 in low (optimal) field and 22 kA cm−2 in 8 T. In the low-field region we observe an anomalous and sharp suppression of I c centred at the zero field. This feature is non-hysteretic for lower temperatures and perpendicular fields, but becomes hysteretic for higher temperatures in perpendicular fields and for all temperatures in parallel fields. The low-field suppression is also reflected in the n-values which can otherwise be very high, in excess of 100 in the optimal field. Magnetic-field hysteresis of I c is generally attributed to flux exclusion/flux trapping in granular superconductors and this is likely to be the case also in the present conductors. The low-field I c anomaly also likely has its origin in planar granularity, while magnetic phases in grains or grain boundaries may also play a role.

History

Preferred citation

Strickland, N. M., Chong, S., Dong, C., Zhang, X., Ma, Y. & Jiang, Z. (2024). Low field anomaly in the critical current of Ba1−X Kx Fe2As2 tapes. Superconductor Science and Technology, 37(7), 075017-075017. https://doi.org/10.1088/1361-6668/ad4f5d

Journal title

Superconductor Science and Technology

Volume

37

Issue

7

Publication date

2024-07-01

Pagination

075017-075017

Publisher

IOP Publishing

Publication status

Published

Online publication date

2024-06-14

ISSN

0953-2048

eISSN

1361-6668

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