Enhanced Magnetic-Flux Pinning Through High-Density Vertically Aligned BaCuO2 Nanorods in Gd0.5Yb0.5Ba2Cu3O7-δ Films

Abstract

A novel flux-pinning design for REBa₂Cu₃O_7-δ (REBCO) films intended for high-field magnet applications is proposed, which is based on BaCuO₂ nanorods in Gd_0.5Yb_0.5Ba₂Cu₃O_7-δ (Gd_0.5Yb_0.5BCO) films. The metal–organic chemical vapor deposition (MOCVD) process has been developed to achieve the desired microstructure. The influence of MOCVD parameters on the microstructure and critical current behavior of Gd_0.5Yb_0.5BCO films is systematically investigated. The morphology and density of BaCuO₂ crystallites within the films are highly sensitive to deposition temperature, oxygen partial pressure, and deposition rate. Notably, forming thin, elongated, vertically aligned BaCuO₂ nanorods requires precise control within a narrow processing window for these three parameters. The optimized MOCVD process results in a dense array of vertically aligned BaCuO₂ nanorods within the Gd_0.5Yb_0.5BCO film, significantly enhancing magnetic-flux pinning, particularly in the low-temperature and high-magnetic-field regime. Superconducting tapes coated with Gd_0.5Yb_0.5BCO films using the optimized MOCVD process exhibit a power-law exponent (α value) of 0.40 for the critical current decay with magnetic field at 4 K, which is substantially lower than that of other REBCO coated conductors reported to date.