Critical current density above 15 MA cm⁻²at 30 K, 3 T in 2.2μm thick heavily-doped (Gd,Y)Ba₂Cu₃Oxsuperconductor tapes

A critical current ( I c ) value of 3963 A/12 mm, corresponding to a critical current density ( J c ) of 15 MA cm −2 has been achieved at 30 K, 3 T in the orientation of field parallel to the c -axis (B||c) in 2.2 μ m thick film (Gd,Y)BaCuO tapes with 20 mol% Zr addition made by metal organic chemical vapor deposition. This J c level is more than a factor of four higher than the J c values of 7.5 mol% Zr-added tapes, which are an industry benchmark. The critical current values in a magnetic field of 3 T parallel to the c -axis in the 2.2 μ m thick, 20 mol% Zr-added tape reached 2833 A/12 mm (10.1 MA cm −2 ), 1881 A/12 mm (7.1 MA cm −2 ) and 805 A/12 mm (3.1 MA cm −2 ) at 40 K, 50 K and 65 K respectively. Such high critical current values were possible because of maintaining a strong alignment of BaZrO 3 nanocolumns along the c -axis over the entire film thickness.