Realization of practical level current densities in Sr_0.6K _0.4Fe₂As₂ tape conductors for high-field applications

122 type pnictide superconductors are of particular interest for high-field applications because of their large upper critical fields H_c2 (> 100 T) and low anisotropy γ (<2). Successful magnet applications require fabrication of polycrystalline superconducting wires that exhibit large critical current density J_c, which is limited by poor grain coupling and weak-link behavior at grain boundaries. Here, we report our recent achievement in the developing Sr_0.6K_0.4Fe ₂As₂ tapes with transport J_c up to 0.1 MA/cm² at 10 T and 4.2 K. This value is by far the highest ever recorded for iron based superconducting wires and has surpassed the threshold for practical application. The synergy effects of enhanced grain connectivity, alleviation of the weak-link behavior at grain boundaries, and the strong intrinsic pinning characteristics led to the superior J_c performance exhibited in our samples. This advanced J_c result opens up the possibility for iron-pnictide superconducting wires to win the race in high-field magnet applications.