Strong correlation between Jc(T, H||c) and Jc(77 K, 3 T||c) in Zr-added (Gd, Y)BaCuO coated conductors at temperatures from 77 down to 20 K and fields up to 9 T

We have conducted a critical current density Jc(T, H) study over a wide temperature T from 77 down to 20 K and a magnetic field H up to 9 T on more than 50 similar to 0.9 mu m-thick REBa2Cu3O7-delta(RE = rare earth) thin films containing different concentrations of BaZrO3(BZO). We found that, independent of the composition, there is a linear correlation between J(c)(77 K, 3 T parallel to c) and J(c)(T,H parallel to c) at T down to 20 K and H up to 9 T. Moreover, J(c)(77 K, 3 T parallel to c) is also linearly correlated to J(c)(T, H parallel to ab) below 40 K. We ascribed this linear correlation to the dominant pinning source of BZO nanorods, which act as a strong correlated pinning at T above similar to 30 K and provide weak uncorrelated point pins at lower temperatures. Our result emphasizes that J(c)(77 K, 3 T parallel to c) is a key metric for metal-organic chemical vapor deposited REBa2Cu3O7-delta coated conductors.