High-Field and Angular Dependence Study of the Critical Current Surface in Modern REBCO Coated Conductors

In the frame of a collaboration between the University of Geneva and Tohoku University, the dependence of the critical current (I<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub>) on magnetic field orientation (Ө), intensity (B) and temperature (T) was characterized on three commercial REBCO tapes from Faraday Factory/SuperOx, SuperPower and Shanghai Superconductor Technology, at temperatures between 4.2 K and 77 K and in magnetic fields up to 19 T in Geneva and 24 T at Tohoku University. Measurements were performed on full-width tapes at University of Geneva, and on patterned microbridges at Tohoku University. Among the three examined tapes, significant variations in the anisotropic landscape of I<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub>(B,T,Ө) were observed (e.g. a single or dominant peak or a secondary peak rising with temperature), reflecting variations in processing methods and pinning centers. Additionally, results emphasize the necessity of full angular scans, as the angular position of the minimum I<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> is observed to depend on T and B and can occur at angles as low as 35°, challenging the typical assumption of the minimum located at 90°, when B is aligned to the c-axis of REBCO. To address such variability, preliminary fits at various T and B are calculated using the maximum entropy model, offering a promising pathway toward efficient scaling relations.