High intergrain critical current density in fine-grain (Ba0.6K0.4)Fe2As2 wires and bulks

Abstract

The K- and Co-doped BaFe2As2 (Ba-122) superconducting compounds are potentially useful for applications because they have upper critical fields (Hc2) of well over 50 T, Hc2 anisotropy Gamma < 2, and thin film critical current densities exceeding 1 MAcm-2 at 4.2 K. However, thin-film bicrystals of Co-doped Ba-122 clearly exhibit weak link behavior for [001] tilt misorientations of more than about 5 degrees, suggesting that textured substrates would be needed for applications, as in the cuprates. Here we present a contrary and very much more positive result in which untextured polycrystalline (Ba0.6K0.4)Fe2As2 bulks and round wires with high grain boundary density have transport critical current densities well over 0.1 MAcm-2 (SF, 4.2 K), more than 10 times higher than that of any other ferropnictide wire. The enhanced grain connectivity is ascribed to their much improved phase purity and to the enhanced vortex stiffness of this low-anisotropy compound (Gamma ~ 1-2) compared to YBa2Cu3O7-x (Gamma ~ 5).

Final version published in Nature Materials

References in corpus (7)

• Advantageous grain boundaries in iron pnictide superconductors
• Fishtail effect and the vortex phase diagram of single crystal Ba0.6K0.4Fe2As2
• Biaxially textured cobalt-doped BaFe2As2 films with high critical current density over 1 MA/cm2 on MgO-buffered metal-tape flexible substrates
• Electromagnetic, atomic-structure and chemistry changes induced by Ca-doping of low-angle $YB{a}_{2}C{u}_3{O}_{7-\delta }$ grain boundaries
• Superconducting properties of SmO1-xFxFeAs wires with Tc = 52 K prepared by the powder-in-tube method
• The critical current of YBa2Cu3O7-d Low Angle Grain Boundaries
• Evidence for electromagnetic granularity in polycrystalline Sm1111 iron-pnictides with enhanced phase purity

Cited by in corpus (5)

• Exploration of new superconductors and functional materials and fabrication of superconducting tapes and wires of iron pnictides
• A new approach for improving global critical current density in Fe(Se0.5Te0.5) polycrystalline materials
• Large, Homogeneous, and Isotropic Critical Current Density in Oxygen-Annealed Fe1+yTe0.6Se0.4 Single Crystal
• Anomalous scaling behavior in a mixed-state Hall effect of a cobalt-doped BaFe2As2 epitaxial film with a high critical current density over 1 MA/cm2
• Anisotropies and Homogeneities of Superconducting Properties in Iron-Platinum-Arsenide Ca10(Pt3As8)(Fe1.79Pt0.21As2)5