SIMULATION OF MAGNETIZATION REVERSAL IN 2-PHASE EXCHANGE-COUPLED NANOCRYSTALLINE MATERIALS

A nanoscale two-phase uniaxially anisotropic material has been numeric ally modeled using a two-dimensional array of micromagnetic. moments t o represent the material on an atomic scale. Demagnetization curves ar e calculated by minimizing the total energy of the system which includ es a component due to exchange interactions between nearest neighbors, as well as magnetocrystalline and magnetostatic energies. Magnetizati on reversal is shown to be initiated in the soft magnetic phase and to proceed by reversible rotation until a critical field, coercivity, at which the magnetization of the system switches irreversibly. As the d imension of the soft magnetic phase increases, coercivity approaches a lower limit and there is a transition from single- to two-phase