Variation in field-dependence of magnetic reversal mechanism with interspin coupling and system size for a two-dimensional classical Ising lattice with barrier dynamics

In order to investigate the variation of reversal mechanism with applied field, a two-dimensional, classical Ising model is constructed with ferromagnetic nearest-neighbor coupling on a square lattice. Magnetization reversal of the lattice is modelled using a master equation approach, with transition probabilities incorporating an energy barrier derived from the Stoner-Wohlfarth model of noninteracting single-domain particles. Field dependence of the dominant reversal mechanism-domain growth or nucleation-is shown to vary with interspin coupling and system size. The transition between these reversal mechanisms, which occurs at the dynamic spinodal field H-DSP, is found to vary linearly with coupling. The magnetic viscosity parameter Lambda-related to Lambda(eff); the rate of change of the mean metastable lifetime with field-is also investigated. Results are compared with analytic approximations for the propagation velocity of a kinetic Ising interface based on calculations presented in P. A. Rikvold and M. Kolesik, Phys. Rev. E 66, 066116 (2002) and related papers.