COMPUTER-SIMULATION OF MAGNETIZATION STATES IN A MAGNETIC THIN-FILM CONSISTING OF MAGNETOSTATICALLY COUPLED GRAINS WITH RANDOMLY ORIENTED CUBIC ANISOTROPY

Computer simulations are performed to model the magnetically soft but isotropic behavior of an Fe-Si-Al alloy film. Solving the Landau-Lifshitz-Gilbert equation under the periodic boundary condition, magnetization states are simulated in a single layer film represented by a two-dimensional array of closely packed hexagonal prisms. Each prism represents a single crystal grain which is assumed to have randomly oriented cubic anisotropy and similar magnetic parameters as those of an Fe-Si-Al alloy film. It is also assumed that the magnetization is always uniform inside each grain and the exchange coupling among grains is zero. It is observed that the film without an external field shows a demagnetized state with considerably dispersed domain configuration where the characteristic wall and vortex structures are formed. It is also observed that the film is switched by applying an external field of which intensity depends on the cubic anisotropy constant of the grains. Analyzing the sum of exerting torque to the magnetization of grains, it is derived that the torque by cubic anisotropy is completely balanced with that by demagnetizing field.