Tailoring coercive field in rare earth giant magnetostrictive materials by α-Fe precipitation

Rare earth giant magnetostrictive materials (GMMs) Tb 1− x Dy x Fe 2± δ (Tb–Dy–Fe) have been successfully employed in many microelectromechanical devices due to their excellent magnetostrictive properties at room temperature. However, Tb–Dy–Fe still shows a relatively large coercivity with high hysteresis, which inevitably limits its application range. Herein, micromagnetic simulations are performed to investigate the size effect of precipitated phase (α-Fe) on coercivity in Tb–Dy–Fe. Simulation results demonstrate that the coercivity is reduced from 31.46 to 12.48 mT with increasing the size of α-Fe from 4 to 50 nm in Tb–Dy–Fe since the precipitated phase of α-Fe can act as a magnetization reversal nucleus. This decreasing trend of coercivity can be well fitted with an inverse square relationship, which agrees well with the nucleation theory. Our study highlights that the coercivity of Tb–Dy–Fe can be tailored by tuning the size of α-Fe precipitation. Graphical abstract