Realization of practical level current densities in Sr_0.6K_0.4Fe₂As₂ tape conductors for high-field applications

Abstract

122 type pnictide superconductors are of particular interest for high-field\napplications because of their large upper critical fields Hc2 (> 100 T), low\nHc2 anisotropy r (< 2), and high thin-film critical current densities Jc (> 1\nMA/cm2 at 4.2 K). Successful magnet applications require fabrication of\npolycrystalline superconducting wires that exhibit large in-field Jc, which is\nlimited by poor grain coupling and weak-link behavior at grain boundaries. Here\nwe report our recent achievement in the developing Sr0.6K0.4Fe2As2 tapes with\ntransport Jc up to 0.1 MA/cm2 at 10 T and 4.2 K. This value is by far the\nhighest ever recorded for iron based superconducting wires and has surpassed\nthe threshold for practical application for the first time. The synergy effects\nof enhanced grain connectivity, alleviation of the weak-link behavior at grain\nboundaries, and the strong intrinsic pinning characteristics led to the\nsuperior Jc performance exhibited in our samples. This advanced Jc result opens\nup the possibility for iron-pnictide superconducting wires to win the race in\nhigh-field magnet applications.\n