REBa₂Cu₃O_y (RE = Rare Earth: REBCO) coated conductors (CCs) derived from Reel-to-Reel Pulsed Laser Deposition (RTR-PLD) are promising to be valuable for magnet applications because of the high superconducting performance and reproducibility [1].  For practical applications, enhancement of critical current density (J_c) in magnetic field for REBCO CCs is needed. So far, by using Trifluoroacetate-metal organic deposition, we have introduced BaHfO₃(BHO) nanoparticles with an incoherent interface to the matrix as flux pinning centers in REBCO CCs, and have succeeded in obtaining isotropic and high J_c for various applied magnetic field angles [2]. However, by using vapor deposition process such as PLD method, since BHO nanorods (NRs) have a coherent interface against the superconducting matrix, critical temperature (T_c) and self-field J_c (J_c^s.f.) decrease with BHO content due to the strain from BHO NRs [3]. In order to improve the in-field J_c in PLD REBCO CCs, it is necessary to control the morphology (shape, size and density) of BHO phase without decreasing T_c and J_c^s.f..

In this work, in order to investigate the effect of BHO content on the microstructure and superconducting properties, we prepared RTR-PLD EuBa₂Cu₃O_y (EuBCO) CCs with various vol.% of BHO dopant. Up to 3 vol.%, c-axis length and T_c do not decrease and J_c^s.f. at 77 K slightly increases. Moreover, the EuBCO+3 vol.%BHO CC shows nearly isotropic angular dependence J_c and highest minimum J_c at 77 K, 3 T in this work. We will discuss the influence of BHO content on the superconducting properties based on crystallinity, carrier density and in-field J_c.

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

References
[1] M. Miura et al., Supercond. Sci.Technol, 23 (2010) 014019.
[2] M. Miura et. al., NPG Asia Materials 9 (2017) e447.
[3] S. Miura et. al., Supercond. Sci.Technol,28 (2015) 065013.

Keywords: Critical Current, RTR-PLD, BaHfO3 NRs, REBCO