Structure and superconductivity characterization along transverse direction of EuBa₂Cu₃O7-δ tape deposited by reel-to-reel multi-plume multi-turn pulsed laser deposition technique

Reel-to-reel deposition is a key technique for continuous production of long REBa 2 Cu 3 O 7- δ (REBCO) tapes, while the transverse uniformity of the tape has not been extensively investigated. This work investigated the transverse variation in both superconducting performance and structural characteristics of long EuBCO tapes fabricated via reel-to-reel multi-plume multi-turn pulsed laser deposition. The J c exhibits pronounced transverse non-uniformity, with the lowest J c at the left edge reaching only ~73% of that at the center part. Structural anaylsis reveals that a strong correlation between this non-uniformity and microstructural variations across the tape width. Loose structures were observed on both tape edges, whereas droplet-shaped particles were exclusively found on the left side. The EuBCO layer in loose structure regions exhibited pronounced arched morphology, which impedes the supercurrent transport. This arched structure is attributed to volumetric expansion induced by the partial decomposition of the buffer and EuBCO layers. These decomposition phenomena are most likely associated with the elevated localized overheating near the tape edges, which hypothetically originates from the torsional stress during helical travelling process of the tape in the reel-to-reel deposition process.