FePt-TiO2 exchange coupled composite media with well-isolated columnar microstructure for high density magnetic recording

We reported the fabrication of (001) textured FePt-TiO2 exchange coupled composite (ECC) media including hard/soft bilayer and multilayer with well isolated columnar microstructures. The magnetic anisotropy of FePt-TiO2 was adjusted by applying various substrate bias during film deposition. The cross-sectional transmission electron microscopy images showed isolated granular microstructures in single hard layer, bilayer, and multilayer media. For the bilayer media, it was observed that both the coercivity and magnetization squareness of composite media decreased with increasing thickness of the soft layer. A soft layer with the thickness of 4 nm was more effective to significantly reduce the switching field and maintain a higher thermal stability factor than that of others. Incoherent switching behavior was observed as the soft layer thickness was increased to 6 nm. For multilayer media, it was found that the out-of-plane coercivity decreased to 6.5 kOe, which was close to half of that of the single hard layer. However, the thermal stability factor of the multilayer media slightly decreased compared with the single hard layer and bilayer media due to finite thickness. The results suggested a way to obtain the adjustable anisotropy for ECC media in high density magnetic recording application. (C) 2010 American Institute of Physics. [doi:10.1063/1.3437044]