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This is a comparative study of the angular critical current ($I_c$) in different REBCO coated conductors (CC) at high magnetic fields ($B < 45$ T) performed with torque magnetometry (US Patent 12,187,540)
The high $I_c$ of REBCO makes transport measurements challenging at low temperatures ($T$) and high $B$, which are crucial for magnet construction and pinning mechanism studies. On the contrary, this is a region where the torque magnetometry works the best, providing a rapid assessment of $I_c(B,T,\Theta)$, where $\theta$ is an angle between field and the normal to the ab plane. The measurements agree well with transport data, where available. The study includes data from over 200 samples and shows significant diversity in $I_c(B,T,\Theta)$ between samples, even when manufactured using the same process. Observed exponential and stretched exponential $I_c$ decays at angles when $B$ is in the vicinity of the ab plane and power function and simple exponential decays far from the ab plane allows to clearly distinguish between weak and strong pinning contributions to overall $I_c$.
The results reveal significant lengthwise $I_c$ variations, especially in tapes cut from the
sides of 12 mm-wide production tapes compared to those cut from the center.
These variations are most pronounced when the field is in the vicinity of the ab plane.
Importantly, flux jumps are observed in samples with thick REBCO layers
and thin stabilizers, underscoring potential thermal instabilities. These findings
provide valuable insights into REBCO tape performance under extreme magnetic fields,
highlighting their relevance for high-field magnet and nuclear fusion applications. Actually, these latest results make the author more confident in REBCO CC application in high field magnets. A. Francis, G. Bradford, A. Xu, R. Ries, D. Larbalestier contributed. NHMFL is funded by NSF DMR2128556 and the State of Florida
