First-order-reversal-curve analysis of rare earth permanent magnet nanostructures: insight into the coercivity enhancement mechanism through regulating the Nd-rich phase

Rare earth permanent magnet nanostructures have attracted intensive interest recently due to the increasing demand for integrated and miniaturized devices. As a typical example, hard magnetic Nd2Fe14B-based nanostructures with desired coercivity have been developed by a reduction-diffusion process and the Nd-rich phase is supposed to be essential to optimize the magnetic properties, whereas the identification and role of the Nd-rich phase have not been addressed so far. Herein, Nd2Fe14B-based nanostructures with different Nd-rich phase contents, Nd15Fe77B8 and Nd14.2Fe78.6B7.2, are rationally prepared by a reduction-diffusion process. The coercivity of Nd15Fe77B8 can reach 5 kOe, which is higher than that of Nd14.2Fe78.6B7.2 of 3.2 kOe. First-order-reversal-curve (FORC) analysis confirms the amorphous paramagnetic Nd-rich phase as pinning centers and reveals magnetic interactions and magnetic domain nature in the two nanostructures. The increase of the Nd-rich phase optimizes microstructures and magnetic interactions, responsible for higher coercivity. This work points out the relationship between the Nd-rich phase, magnetic interactions, microstructures, and magnetic properties, and could usher in new ways of fabricating advanced permanent magnetic nanostructures.

Automated summary

Rare earth permanent magnet nanostructures, specifically Nd2Fe14B-based nanostructures, were fabricated with different Nd-rich phase contents, showing that an increase in Nd-rich phase can enhance coercivity due to its role as pinning centers optimizing microstructures and magnetic interactions. This study sheds light on the relationship between Nd-rich phase, magnetic interactions, microstructures, and magnetic properties, paving the way for advanced permanent magnetic nanostructure fabrication techniques.