REBa₂Cu₃O_y (RE = Rare Earth: REBCO) coated conductors (CCs) is expected to be used in high magnetic field applications such as magnets because of its excellent critical current density (J_c) in magnetic fields. However, further improvement of J_c is required for practical use. In order to improve J_c in magnetic fields, BaMO₃ (BMO: M: Hf, Zr, etc.) nanorods and nanoparticles have been introduced into REBCO CCs as flux pinning centers [1-3]. An alternative approach is to introduce defects structures using electron, proton, neutron, or ion irradiation. Recently, Y. Zhang et al. reported that improves J_c in REBCO CCs after irradiation with Au ions [4].

In this work, we prepared the Reel-to-Reel Pulsed Laser Deposition (RTR-PLD) (Eu,Er)Ba₂Cu₃O_y+BaHfO₃ ((Eu,Er)BCO+BHO) CCs with various irradiation fluences of O²⁺ ions to investigate the effect of irradiated defects on the superconducting properties of REBCO+BHO CCs. The (Eu,Er)BCO+BHO CCs with irradiated defects show lower T_c^onset and T_c^zero compared to that of before irradiation. On the other hand, J_c in magnetic field is improved for (Eu,Er)BCO+BHO CCs with irradiated defects. The sample with 1×10¹³ ion/cm³ O²⁺ ions sample shows highest minimum J_c in this work at over a broad temperature. Detailed microstructural and superconducting properties for REBCO CCs with irradiated defects will be presented.

Acknowledgements: This work at Seikei University is supported by JST-FOREST (Grant Number JPMJFR202G). This work at AIST was supported by the New Energy and Industrial Technology Development Organization (NEDO).