Critical Properties of Bulk-Doped BaFe2As2 Pnictides for Magnet Design

• Published in: IEEE transactions on applied superconductivity 2018-04, Vol.28 (3), p.1-4
• Main Authors: Nikolo, Martin, Weiss, Jeremy D., Singleton, John, Jianyi Jiang, Hellstrom, Eric E.
• Format: Article
• Language: English
• Subjects: Critical current density (superconductivity); Grain size; Granularity; High Magnetic Field Science; Magnetic anisotropy; Magnetic field measurement; Magnetic fields; pnictide supercondcutors; pnictides; Superconducting magnets; superconductors; upper critical magnetic fields
• ISSN: 1051-8223; 1558-2515
• DOI: 10.1109/TASC.2017.2775580

A comprehensive study of upper critical (H c2 ) and irreversibility magnetic fields (H irr ) in (Ba 0.6 K 0.4 )Fe 2 As 2 (critical temperature T c = 38.3 K), Ba(Fe 0.95 Ni 0.05 ) 2 As 2 (T c = 19.2 K), Ba(Fe 0.94 Ni 0.06 ) 2 As 2 (T c = 18.5 K), Ba(Fe 0.92 Co 0.08 ) 2 As 2 (T c = 23.2 K), and Ba(Fe 0.91 Co 0.09 ) 2 As 2 (T c = 25.3 K) polycrystalline bulk pnictide superconductors with different average grain sizes was made in pulsed fields at the Los Alamos National Laboratory. The magnetic field-temperature (H c2 -T) phase diagrams with H c2 as high as 65 T at 28 K for the K-doped samples and critical current density (Jo) measurements as high as 105 A/cm 2 for the smallest, submicrometer grain size samples were obtained. The high H c2 , H irr , and J c data show the suitability of these materials for magnet design as their mechanical strength and random grain alignment show promise in the manufacturing of next-generation magnets.