Trapped magnetic field of a superconducting bulk magnet in high-T_c RE-Ba-Cu-O

Superconducting magnets made of high-T_c superconductors are promising for industrial applications. It is well known that REBa₂Cu₃O_7-x and LRE (light rare-earth) Ba₂Cu₃O_7-x superconductors prepared by melt processes have a high critical current density, J_c, at 77 K and high magnetic fields. Therefore, the materials are very prospective for high magnetic field application as a superconducting permanent/bulk magnet with liquid-nitrogen refrigeration. LREBaCuO bulks, compared with REBaCuO bulks, exhibit a larger J_c in high magnetic fields and a much improved irreversibility field, H_irr, at 77 K. In this study, we discuss the possibility and trapped field properties of a superconducting bulk magnet, as well as the melt processing for bulk superconductors and their characteristic superconducting properties. One of the applications is a superconducting magnet for the future magnetically levitated (Maglev) train.