INTERFACE LOCALIZATION IN THIN FERROMAGNETIC-FILMS

Interface localization in a thin ferromagnetic film with competing sur face fields has been investigated by Monte Carlo simulation for an ani sotropic Heisenberg model as a function of temperature and the anisotr opy of the exchange interaction Lambda. In the isotropic model limit, where Lambda --> 0, no spontaneous magnetization of the film is observ ed and the magnetization profile across the film is antisymmetric, slo wly varying from positive magnetization on one surface to negative on the other. However, in the limit Lambda --> 1, when the model Hamilton ian is equivalent to that of the Ising model, a non-zero magnetization of the film is observed below a critical temperature T-c. This is ass ociated with a localization of the interface between regions of positi ve and negative magnetization near the film surface and a degeneracy i n the magnetization profiles exists between states of positive and neg ative total magnetization at low temperatures. The results of magnetic relaxation studies indicate that the magnetization decays exponential ly with a relaxation time that increases with Lambda and decreases wit h temperature.