Micromagnetic study of CoPt–SiO2 granular films by spin-wave Brillouin scattering

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Abstract
A spin-wave Brillouin scattering study of a CoPt–SiO2 granular magnetic recording medium was made. This film contains ferromagnetic CoPt particles in a SiO2 matrix, and has an extremely low medium noise property due to little exchange coupling between magnetic grains. Spin waves of both the propagating surface mode and standing wave mode were found to be excited in granular magnetic films with various microstructures. A possible origin of the spin wave is a magnetostatic coupling between regularly ordered CoPt grains, as reported for artificially patterned magnetic thin films. This result shows two promising features of the CoPt–SiO2 granular film for high density recording medium: It is an ordered media obtained in a self-organizing manner, and it is less influenced by the thermal fluctuation effect, which is a serious problem for current high density magnetic recording.