Over 15 MA/cm of critical current density in 4.8 µm thick, Zr-doped (Gd,Y)BaCuO superconductor at 30 K, 3T.

An Advanced MOCVD (A-MOCVD) reactor was used to deposit 4.8 µm thick (Gd,Y)BaCuO tapes with 15 mol% Zr addition in a single pass. A record-high critical current density (J ) of 15.11 MA/cm has been measured over a bridge at 30 K, 3T, corresponding to an equivalent (I ) value of 8705 A/12 mm width. This corresponds to a lift factor in critical current of ~11 which is the highest ever reported to the best of author's knowledge. The measured critical current densities at 3T (B||c) and 30, 40 and 50 K, respectively, are 15.11, 9.70 and 6.26 MA/cm, corresponding to equivalent Ic values of 8705, 5586 and 3606 A/12 mm and engineering current densities (J ) of 7068, 4535 and 2928 A/mm. The engineering current density (J ) at 40 K, 3T is 7 times higher than that of the commercial HTS tapes available with 7.5 mol% Zr addition. Such record-high performance in thick films (>1 µm) is a clear demonstration that growing thick REBCO films with high critical current density (J ) is possible, contrary to the usual findings of strong J degradation with film thickness. This achievement was possible due to a combination of strong temperature control and uniform laminar flow achieved in the A-MOCVD system, coupled with optimization of BaZrO nanorod growth parameters.