Trapping a magnetic field of 14.8 T using stacked coated conductors of 12 mm width

We fabricated a compact (13 × 12 × 12.5 mm3) trapped-field magnet by stacking 200 pieces of EuBa2Cu3O7 coated conductors (CCs) with BaHfO3 nanorods as artificial pinning centers. It was magnetized by field-cooling method using a 18 T superconducting magnet, and the maximum field of 14.8 T was trapped at 10 K at a field-ramp rate of 0.1 T min-1. At higher temperatures, although the trapped field was decreased, we could trap the field with much faster ramp rate. In order to understand these results, we also performed calculations of the trapped field based on Jc -H characteristics of the CC. The calculated trapped field value was larger than the experimental value at 10 K. This discrepancy can be understood by considering the reduction of the effective size of the stacked CCs due to the existence of extended regions of irregular flux penetration called 'flux jets'.