Relevant Pinning for ab-Plane Jc Enhancement of MOCVD REBCO Coated Conductors

For REBa
₂
Cu
₃
O
_x
(REBCO, where RE = rare earth) coated conductor applications, the prominence of the background magnetic field H in the orientation of ab-plane urges an immediate and proper understanding of the ab-plane pinning and in turn, the critical current density J
_c
tuning. In this work, we present our ab-plane pinning study of metal organic chemical vapor deposited (MOCVD) REBCO coated conductors based on our previous observation of a strong linear correlation between J
_c
at 77 K and J
_c
at lower temperatures T and higher magnetic fields H. In this work, we found that, below ~40 K, besides the weak uncorrelated pinning, the intrinsic pinning due to the layered crystal structure of REBCO with charge reservoir CuO planes also plays an essential role for J
_c
(T, H||ab). Such intrinsic pinning is independent of H, and increases with decreasing T. Combined with the microstructure and J
_c
(T, H, θ) analysis, we found that, at T above ~40 K, strong correlated pinning centers, such as stacking faults and RE
₂
O
₃
precipitates, govern J
_c
(T, H||ab). Our work provides an understanding of ab-plane pinning in Zr-added REBCO coated conductors and guidance for further J
_c
(T, H) enhancement.