The levitation forces for both free sintered and melt-powder-melt-growth (MPMG) yttrium-barium-copper-oxide (YBCO) superconductors have been measured by a torsion balance. The results agree with data obtained by other experimental groups. These levitation forces also have been calculated theoretically by taking into account both the Meissner effect and the induced current due to the critical state of the superconductor. Acceptable agreements are obtained. It is found that the large area enclosed by the hysteretic levitation curve corresponds to a large critical current density of the superconductor.
Chinese Journal of Physics=中國物理學刊 32(5-I)，頁497-503