Micromagnetic correlations in thin films

The influence of the structure defects on the micromagnetic properties of a thin film is investigated by means of the normalized autocorrelation ρm(r) of the magnetization. This concept leads to a natural understanding of the so-called "coupling volume" of HOFFMANN\´s ripple theory. Particularly we discuss HARTE\´s "random anisotropy model" on the basis of a realistic distribution of the size D of the crystallites in a polycrystalline material. Our numerical results reveal that the classical ripple theories have shortcomings, if the parameters of a film considerably differ from those of a typical permalloy film. Just that is the case in a number of modern materials considered for application.