Properties of praseodymium permanent magnet for cryogenic hybrid magnet

Fuwa, Yasuhiro   ; Iwashita, Yoshihisa*; Kondo, Akihiro*

High-field magnets are often demanded advanced scientific studies. Although a hybrid coil design comprising Nb-Ti, NbSn, and HTS (High-Temperature Superconductors) are potential candidates for such application, the costs of NbSn and HTS are expensive compared with Nb-Ti. By generating an additional field of about 1 T by permanent magnets, the required amounts of superconducting material may be reduced. Magnetic properties of some magnetic materials have been studied by other works at temperatures as low as 100 K. The remanent field of conventional NdFeB magnets decreases at 100 K due to spin reorientation. PrFeB magnets consisting of praseodymium (Pr) instead of neodymium (Nd) do not show such degradation and the coercivity of PrFeB at 100 K is 7 T. In this study, the B-H curve, as a primary magnetic property, of a PrFeB magnet sample was measured in the temperature range down to 4 K. As a result, no decrease in magnetization of the praseodymium magnets, and the coercivity was 10 T.