Anisotropy and pinning field in nanocomposite magnetic materials

The pinning fields of domain wall at different grain boundary H 0 have been calculated based on the given expression of anisotropy at grain boundary. The coercivity of nanocomposite magnetic materials is thought to be determined by H 0 . Compared with the experiential formula of coercivity, the expression of exchange–coupling coefficient α ex corresponding to pinning fields on grain size D was given too. The results showed that H 0 and α ex increase rapidly first, then increase slowly with increasing D . Our results are consistent with the relative theoretical and experimental results given by others.