Effect of the grain alignment on the levitation force in single domain YBa₂Cu₃O_y bulk superconductors

Single-domain YBa₂Cu₃O_y (YBCO) bulk superconductors (Φ 30×15 mm³) with high levitation force of 70 N have been fabricated by modified melt-textured growth process. The sample was cut into a group of small rectangular samples with the same dimension of 3.5×3.5×5 mm³ along different grain-orientation. The levitation force of the small samples has been measured at liquid nitrogen temperature. It is found that the levitation force decreases monotonously from θ = 0° to 90°, where θ is the angle between the c-axis and the normal to the polished surfaces. A simple model has been proposed to interpret the experimental result, which is in good agreement with the experimental data.