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

Abstract

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 ∼ 0.9 μm-thick REBa2Cu3O7−δ (RE = rare earth) thin films containing different concentrations of BaZrO3 (BZO). We found that, independent of the composition, there is a linear correlation between Jc(77 K, 3 T||c) and Jc(T, H||c) at T down to 20 K and H up to 9 T. Moreover, Jc(77 K, 3 T||c) is also linearly correlated to Jc(T, H||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 ∼30 K and provide weak uncorrelated point pins at lower temperatures. Our result emphasizes that Jc(77 K, 3 T||c) is a key metric for metal-organic chemical vapor deposited REBa2Cu3O7−δ coated conductors.