Magnetostatic interactions in films for perpendicular recording media

The magnetostatic interactions in CoCr films for perpendicular recording are studied, based on the measuremenrt of ordinary nagnetization curves. The method used does not need the evaluation of the remanent magnetization curves, which is difficult to obtain in these media because of the presence of demagnetizing field in the anisotropy direction. The obtained interaction effects are related with the film thickness, Cr content, the presence of Fe81Ni19 underlayer, and the magnetic properties of the recording media. The interactions are strong in films with large thickness and they are weak when the thickness is small and even weaker in double layer FeNi/CoCr films. This result is correlated with the magnetization reversal mode, which evolves towards incoherent mechanisms when the film thickness decreases and even more in double layers, as a consequence of the greater dispersion in the vertical columnar structure of the CoCr films.