[WB4] Advanced Processing

11:15 AM - 11:30 AM JST(2:15 AM - 2:30 AM UTC)

[WB4-04] Co-doping with BaSnO₃ and BaHfO₃ by Ultra-high Rate PLD Enabling Formation of High-density Nanocolumns in EuBa₂Cu₃O_7-δ Films

*Yue Wu¹, Mengrui Zhao¹, Chunsheng Chen², Yuji Tsuchiya³, Tatsunori Okada⁴, Junyi Luo³, Satoshi Awaji³, Yue Zhao^1,2 (1. Shanghai Jiao Tong University (China), 2. SuperMag Tehcnology (Shanghai) Co., Ltd. (China), 3. Institute for Materials Research, Tohoku University (Japan), 4. Department of Materials Science and Engineering, Kyushu Institute of Technology (Japan))

Keywords:

High-temperature superconductor,Pulse laser deposition,Defects engineering,Diffusion,Nanocolumns

Introduction of artificial pinning centers through defects engineering is an effective strategy to mitigate the reduction of in-field current carrying capacity of REBCO tapes. However, it is challenging for formation of high-density columnar secondary phase while maintaining the high crystallinity of REBCO at high-speed deposition during the pulsed laser deposition (PLD) process, which restricts mass production of high-performance tapes for high-field magnet applications. In this work, a BaHfO₃+BaSnO₃ co-dopant strategy was utilized to modulate the microstructure of doped EuBa₂Cu₃O_7-δ (EuBCO) films via reel-to-reel multi-plume and multi-turn PLD with ultra-high rate (exceeding 100 nm/s). These nanocolumnar structures, composed of BaSnxHf_1-xO₃ (BSHO) at the atomic scale, were aligned along the thickness direction throughout the EuBCO layer. The high-density nanocolumns, ∼ 5 nm diameter, exhibited an areal density of about 2200 pieces/μm² . This unique microstructure significantly enhanced the in-field J_c of co-doped film. At 50 K and 3 T, the J_c reaches ∼4.0 MA/cm² at perpendicular field, exceeding that at parallel field. Notably, even under a higher field (50 K and 8 T), the J_c(θ) curve of the co-doped film exhibits a pronounced correlated pinning peak in the perpendicular field. The large in-plane lattice mismatch between the BSHO and EuBCO leads to the formation of semi-coherent interfaces, which introduce numerous nanoscale defects acting as random pinning centers under high fields. High-field superconductivity measurement results indicate that the pinning force displays non-saturation phenomenon at 4.2 K up to 24 T, achieving a high value of ∼990 GN/m³ .