ΔM study of perpendicular recording media

A significant source of media noise in thin-film granular systems is intergranular exchange coupling. This important interaction between grains in longitudinal recording media has been studied by well-established DeltaM(H) techniques. In this study, micromagnetic calculation using a Monte Carlo simulation has been carried out to confirm the validity of such a technique for perpendicular media. A recently developed demagnetization correction method is applied to a series of alloy perpendicular media, and subsequently, the exchange interactions in these films are studied using the DeltaM(H) technique. With increasing film thickness, DeltaM(H) changes from positive to negative, indicating a reduction of the exchange interaction in thicker films. This reduction is attributed to a stronger exchange coupling between grains at the initial stage of the film growth. (C) 2003 American Institute of Physics.