Irreversible magnetization processes in a soft magnetic platelet

The influence of an applied field on the magnetic domain structure of a permalloy platelet (3.2 mu m x 1 mu m x 80 nm) is studied by means of micromagnetic finite element modeling. Starting from two different demagnetized domain states with nearly closed flux, a magnetic field is applied in-plane and increased stepwise. The magnetization process is determined by the motion of domain walls and domain structure conversion. Irreversible processes occur when 180 degrees walls intersect an edge of the sample or when two domain walls cancel each other. A repetitive repositioning of the discretization points is used to both avoid numerical grid pinning effects and to reduce discretization errors. The numerical results compare favorably with experimental observations. (C) 2000 Elsevier Science B.V. All rights reserved.