Recent Progress of $\hbox{MgB}_{2}$ Bulk Magnets Magnetized by Pulsed Field

A MgB
₂
superconducting bulk has a promising potential as a quasi-permanent magnet. In this paper, we have performed pulsed-field magnetization (PFM) at T
_s
= 14-20 K for MgB
₂
superconducting bulks with a higher critical current density J
_c
(B) fabricated by hot isostatic pressing. During PFM, a flux jump frequently took place, and trapped field B
_z
decreased in the disk-shaped bulks for a higher magnetic field application. However, in the cylindrical bulk with identical J
_c
(B) characteristics, the flux jump was avoided, and a maximum trapped field of Bz = 0.81 T was obtained at 14 K, which is a record-high trapped field in a MgB
₂
bulk by PFM. The electromagnetic and thermal instability was discussed using conventional relations to avoid the flux jump and to enhance the trapped field on the MgB
₂
bulks with higher J
_c
(B), higher thermal conductivity, and lower specific heat.