Effect of defects on the effective anisotropy and coercivity in nanometer hard magnetic materials

The effects of defects and intergrain exchange interactions on the effective anisotropy K eff and coercivity have been investigated in nanometer hard magnetic materials. The results showed K eff and coercivity simultaneously influenced by defects and intergrain exchange interactions are smaller than that only influenced by the latter. This indicates that the existence of defects decreases K eff and coercivity. And the K eff and coercivity reduce with increasing the thickness r 0 of the defect. The coercivity we calculated is consistent with the experimental results given by Manaf et al.