In order to investigate magnetic viscosity in thin films, a two-dimensional single phase classical Ising model was constructed with the standard Ising Hamiltonian modified to include an additional uniaxial anisotropy term. Variation of magnetisation with time using this model was calculated by a Monte Carlo simulation on a 100 x 100 lattice with nearest neighbour interactions. The Monte Carlo algorithm developed for the modified Hamiltonian shows magnetic viscosity towards the anhysteretic state on major loops, and viscosity initially away from the anhysteretic state on minor (recoil) loops. This latter viscosity has only been experimentally observed in two-phase exchange-spring magnets, whilst our model is a single-phase system.
Eilon, M., Thompson, P. J., Geoghegan, D. S., & Street, R. (1997). A classical Ising model and magnetic viscosity in thin films. Journal of Magnetism and Magnetic Materials, 175, 249-254. https://doi.org/10.1016/S0304-8853(97)00269-2