Flux Pinning Properties of BaHfO₃-Doped YBa₂Cu₃O_y Coated Conductors Fabricated at Various Substrate Temperature and Thickness Per Pulse by Pulsed Laser Deposition with Substrate Self-Heating Technique

Abstract

In superconducting coil applications, magnetic fields are applied to superconducting material from various directions. YBa₂Cu₃O_y (YBCO) coated conductor containing BaHO3 (BHO) flux pinning centers is expected to be used as coil application. In this study, BHO-doped YBCO films were prepared by changing the substrate temperature (T_s) and thickness per pulse (t_pulse) using the pulsed laser deposition method. As a result, the isotropy of the critical current density vs field angle (J_c-θ) curve was improved in the BHO-doped YBCO film fabricated under the condition of low T_s and high tpulse. In the cross-sectional transmission electron microscopic observation, it was confirmed that BHO nanorods with gradually increasing tilt angles grew in BHO-doped YBCO film. The surface atomic force microscope images also confirmed that YBCO grains grew in three-dimensional island growth. The shape of BHO is determined by the growth rate of YBCO and BHO, which affects the tilt angle of the BHO nanorods.