Irradiation-Induced Defect Engineering in REBCO Coated Conductors: Mechanisms, Effects, and Perspectives

REBa₂Cu₃O_7−δ (REBCO) coated conductors are considered a critical material for next-generation high-field superconducting applications owing to their superior superconducting performance at elevated temperatures and under strong magnetic fields. However, rapid degradation of the critical current density ($J_c$) under high-field and high-temperature conditions remains a major limitation for their practical applications. To address this, controlling flux pinning centers has emerged as a crucial strategy to enhance performance. Irradiation techniques, as one of the most commonly employed methods, have attracted considerable attention due to their capability to provide precise control, high reproducibility, and flexibility in tailoring the microstructure. In this review, we focus on the effects of proton, heavy-ion, and neutron irradiation on the microstructure and superconducting properties of REBCO coated conductors. We discuss the underlying mechanisms in terms of defect types and distributions, energy loss processes, flux pinning enhancement, and the evolution of $J_c$ and transition temperature ($T_c$). Furthermore, we compare different irradiation methods, highlighting their advantages and suitability across diverse temperature and magnetic field conditions. The potential of hybrid irradiation strategies for creating multiscale composite pinning landscapes is also examined. Future efforts should aim to synergistically combine different irradiation mechanisms and optimize defect structures to develop REBCO tapes with highly isotropic and stable flux pinning, which is essential for large-scale applications in fusion energy, high-field magnets, and aerospace electric motors.