Exchange-coupling interaction, effective anisotropy and magnetic property of nano-magnetic materials

The theories and models of exchange-coupling interaction between grains in nanocrystaUine magnetic materials are introduced here. Their insufficiencies and distinctions from the experimental results are pointed out, and some revisions are made. The effects of the phase component ratio, the grain size and on the effective anisotropy and mngnetic properties in the nanocomposite permanent materials and the improved models are discussed in detail.