Significant improvement of critical current density in MgB₂doped with ferromagnetic Fe₃O₄nanoparticles

Abstract

Ferromagnetic Fe3O4-doped MgB2 bulks were first fabricated in this work by the hot pressing method. It was found that Fe3O4 does not react with Mg or B during the fabrication process. Peak Jc values of the 5 wt% Fe3O4-doped MgB2 are higher than 106 A cm−2 in the temperature range 5–30 K. Especially at 30 K, the peak Jc is 1.02 × 106 A cm−2 for the 5 wt% Fe3O4-doped MgB2, the highest values at 30 K found in the literature, and about seven times that of the 5 wt% SiC-doped MgB2 sample. The drop in Jc with increasing field for the Fe3O4-doped MgB2 is significantly slower than that of the SiC-doped MgB2 at 30 K. These results indicate that the Fe3O4-doped MgB2 is a potential superconductor to be used at temperatures greater than 25 K which is a critical temperature for large-scale practical applications.