High and uniform critical current density for large-size YBa2Cu3O7−δ single crystals

A top seed melt growth method was adapted to grow a 4 × 4 × 1.5 cm3 YBa2Cu3O7−δ single crystal. We cut this single crystal into five different parts and investigated the critical current density while applying a magnetic field perpendicular to the CuO2 plane. The information extracted from five different spots showed no significant Jc difference except at the center and the corners. The measured Jc, on the order of 106 A/cm2 for H = 0 at 5 K, was remarkably high, which indicated that this large crystal could be very useful for large-scale applications such as superconducting bearings or fly-wheel systems.