EFFECTS OF SURFACE ANISOTROPY ON HYSTERESIS IN FINE MAGNETIC PARTICLES

We solve numerically the dissipative Landau-Lifshitz-Gilbert equations to consider hysteresis in fine magnetic particles. Finite-size effect s are studied for two models with uniaxial anisotropy - bulk random ax is and surface anisotropy only. It is demonstrated that the latter mod el introduces considerable effects for small enough particles when the coupling to the anisotropy is equal or greater than the coupling to t he isotropic Heisenberg exchange. We show that some features of magnet ization reversal are associated with spins at the surface of fine part icles.