Remanence enhancement in nano-structured composite magnets

The remanence of an isotropic nanocrystalline exchange-coupled composite sy stem (comprising hard and soft magnetic phases) is investigated analyticall y within a simple (one-dimensional) micromagnetic model, in which only exch ange and anisotropy energies are considered. For a soft grain with size muc h less than its own Bloch wall width, our analysis shows that the magnetiza tion distribution in the soft phase is linearly dependent upon position, wh ich we show is responsible for the significant enhancement observed in comp osite systems. Furthermore, we show that a good estimate of the remanence c an be provided by a simple formula, which is easily calculated by hand.