Quantification of intergranular exchange coupling in CoPtCr-based perpendicular recording media via ferromagnetic resonance measurements

Intergranular exchange fields in CoPtCr granular media materials were quantified through ferromagnetic resonance measurements in various magnetic states. The data indicate that the exchange field in CoPtCr granular films with no oxide segregant is comparable to the saturation magnetization of the films. With an introduction of a SiO2 segregant, however, the exchange field decreases. A 30% volume fraction of the segregant reduces the strength of the intergranular exchange coupling to zero.