Micromagnetic localization

The localization of nucleation modes in inhomogeneous ferromagnets and its influence on the coercivity are investigated. From the formal analogy betwe en quantum mechanics and micromagnetics follows that anisotropy inhomogenei ties may cause localization. The nucleation modes of one-dimensional arrays , such as multilayers composed of hard and soft magnetic materials, are loc alized even if the superlattice exhibits a nearly ideal periodicity. Gaussi an distributions of the layer thicknesses lead to Urbach tails and very low coercivities, but a maximum thickness l(m) of the soft layers suppresses t he Urbach tails. The related problem of magnetic viscosity leads to a super symmetric Fokker-Planck description where the time dependence of the magnet ization is given by the ground-state mode of a fermionic potential. (C) 199 8 American Institute of Physics. [S0021-8979(98)50911-5].