Additional Pinning Effect by Heavy-Ion Irradiation in Coated Conductors with Artificial Pinning Centers

We investigated additional pinning effect on in-field J_c properties of coated conductors including Y₂O₃ nano-particles as artificial pinning centers (APCs), where three types of heavy-ion beams were employed with the fluence of 4.84 × 10¹⁰ to 7.26 × 10¹¹ ions/cm². The addition of the irradiation defects enhanced the in-field J_c. Furthermore, more upward shift in the J_c was observed for the introduction of the defects with larger volume of the irradiation damage, not only in high magnetic fields but also in low magnetic fields. One factor of the irradiation effect is that the self-field J_c and the critical temperature T_c are relatively insensitive to the addition of the irradiation defects for the samples with APCs. Another is the glassy flux creep behavior over wide temperature region, suggesting that flux pinning by the combination of APCs and irradiation defects is strong against thermal fluctuation.