A CLASSICAL ISING-MODEL AND MAGNETIC VISCOSITY IN THIN-FILMS

In order to investigate magnetic viscosity in thin films, a two-dimens ional single phase classical Ising model was constructed with the stan dard Ising Hamiltonian modified to include an additional uniaxial anis otropy term. Variation of magnetisation with time using this model was calculated by a Monte Carlo simulation on a 100 x 100 lattice with ne arest neighbour interactions. The Monte Carlo algorithm developed for the modified Hamiltonian shows magnetic viscosity towards the anhyster etic state on major loops, and viscosity initially away from the anhys teretic state on minor (recoil) loops. This latter viscosity has only been experimentally observed in two-phase exchange-spring magnets, whi lst our model is a single-phase system.