Remanence enhancement in nano-structured composite magnets

The remanence of an isotropic nanocrystalline exchange-coupled composite system (comprising hard and soft magnetic phases) is investigated analytically within a simple (onedimensional) micromagnetic model, in which only exchange and anisotropy energies are considered. For a soft grain with size much less than its own Bloch wall width, our analysis shows that the magnetization distribution in the soft phase is linearly dependent upon position, which we show is responsible for the significant enhancement observed in composite systems. Furthermore, we show that a good estimate of the remanence can be provided by a simple formula, which is easily calculated by hand.