Microstructure and Superconducting Properties of Yttrium Barium Copper Oxide Thin Film With Patterned Substrates for Ultra-Fine Multi-Filaments

Yttrium barium copper oxide (YBCO) superconductors are promising candidates for superconducting magnets operating at low temperatures and high magnetic fields, as well as for advanced electric power devices. Commercially available YBCO wires are manufactured in tape form, by depositing a thin YBCO layer atop multiple buffer layers on a metal substrate. This coated conductor structure closely resembles a single crystal, with well-aligned crystallographic axes, thereby exhibiting high critical current densities. However, challenges remain in reducing screening currents and AC losses for practical applications. In this study, we present a multifilamentary YBCO thin film design with patterned elevated stripes, fabricated using photolithography on substrates. Various stripe materials, including SiO2, and Al2O, were evaluated by depositing YBCO on the STO/stripe structures. Magnetooptical imaging demonstrated that non-superconducting stripes separate the superconducting regions, irrespective of the stripe material used. Transmission electron microscopy (TEM/STEM)-EDX analysis revealed that YBCO on STO/SiO₂ stripes formed crystals with varied orientations, whereas STO/Al₂O₃ stripes resulted in the formation of impurity phases. These findings indicate that substrate patterning with stripe structures is a viable approach for realizing multifilamentary coated conductors, potentially reducing AC losses and enhancing future superconductor applications.