Highly c-axis orientated superconducting core and large critical current density in Ba_0.6Na_0.4Fe₂As₂ powder-in-tube...

Improvement of the critical current density (J_c) of superconducting wires/tapes is one of the key issues in the field of superconductivity applications. Here we report the fabrication of a silver-sheathed Ba_1-xNa_xFe₂As₂ (BaNa-122) superconducting tape by using a powder-in-tube technique and its superconducting properties, in particular transport J_c, as well as the tape-core texture. The optimally-doped BaNa-122 tape with Na concentration x = 0.4 exhibits the superconducting critical temperature (T_c) of 33.7 K and high transport J_c of 4 × 10⁴ A/cm² at 4.2 K in a magnetic field of 4 T. Patterns of x-ray diffraction for the superconducting core show that the degree of c-axis orientation is significantly enhanced through the tape fabrication process. The tendency of c-axis orientation is advantageous for achieving higher J_c, suggesting the high potential of BaNa-122 for superconducting wire/tape applications.