Two- and three-dimensional calculation of remanence enhancement of rare-earth based composite magnets (invited)

TLDR

The study aims to use micromagnetic finite element calculations to describe the magnetic properties of novel, isotropic rare‑earth‑based composite magnets. The authors employ a finite element micromagnetic approach to model the magnetic behavior of these composites. Numerical results show that remanence, coercivity, and squareness depend sensitively on microstructure, with interparticle exchange boosting remanence by ~60 % and suppressing domain nucleation, leading to optimally structured composites achieving energy products over 400 kJ m⁻³.

Abstract

Micromagnetic calculations using a finite element technique rigorously describe the magnetic properties of novel, isotropic rare-earth-based composite magnets. Numerical results obtained for a composite material of Nd2Fe14B, SmCo5 or Sm2(Fe0.8Co0.2)17N2.8 and α-Fe particles show that remanence, coercivity, and coercive squareness sensitively depend on microstructural features. Interparticle exchange interactions enhance the remanence by about 60% with respect to noninteracting particles for a mean-grain size approaching the exchange length of the soft magnetic phase and a significant percentage of α-Fe. On the other hand, exchange interactions between the phases suppress the nucleation of reversed domains and thus preserve a high coercive field. Therefore, optimally structured, isotropic composite magnets show remarkably high energy products exceeding 400 kJ/m3.