Computer simulation of magnetization reversal in fine hexaferrite particles

Magnetization reversal mechanisms in hexaferrite particles were investigated by computer simulation. The Landau–Lifshitz–Gilbert equation discretized according to the Crank–Nicolson method was solved numerically. The computing region was divided into triangular prisms of equal size which are accommodated to the contour surfaces of the hexagonal particle. The demagnetizing field was calculated using a finite-grid method based on the triangular prisms. The mode of reversal was found to be extremely dependent on the thickness of the particle. In the case of a thin particle, the reversal started at the particle center and then spread to the edges of the particle almost coherently at the same radius. In a thick particle, vortexes of magnetization with opposite polarities of rotation were generated at the top and bottom surfaces, and the switching was incoherent over the particle thickness. In the case of an intermediate thickness, the reversal began at the particle center, but it spread to the particle edges incoherently. The formulation of the calculation and the results of simulation are given.