Understand High Track Density in Heat Assisted Magnetic Recording

Granular FePt media with perpendicular L10 ordering yields alternating Fe and Pt monolayers within a grain. A Pt monolayer could become a boundary that separates oppositely magnetized domains since it would yield zero ferromagnetic exchange coupling between the two neighboring Fe monolayers. This mechanism facilitates the formation of multidomain states for the grains at recorded transitions, significantly reducing the transition noise caused by the binary nature of the grain magnetization. Such mechanism is likely responsible for the high track density capability demonstrated in current heat assisted magnetic recording (HAMR) technology. The study also investigated thermal erasure noise characteristics as function of recording temperature, enabling direct experimental check on practical HAMR media to verify the proposed hypothesis.