Granular nanostructures and magnetic properties of FePt–C/FePt–SiO2 films

• High coercivity and strongly (001) texture were obtained in FePt–C/FePt–SiO2 films.
• Using FePt–C/FePt–SiO2 structure can get low magnetic coercive force distribution.
• Columnar FePt grains with large aspect ratio were obtained in FePt–C/FePt–SiO2 films.
• FePt–C/FePt–SiO2 films are very suitable for heat assisted magnetic recording media.

FePt–C, FePt–SiO2 and FePt–C/FePt–SiO2 films with different segregants concentration on glass substrate with polycrystalline MgO underlayer have been successfully fabricated by magnetron sputtering system. It was found that the FePt–C films had larger coercivity(Hc), chemical order parameter(S) and smaller diameter of the local interaction zone(Dn) but wider magnetic coercive force distribution(ΔHc/Hc) than that of the FePt–SiO2 films. By using FePt–C/FePt–SiO2 bilayer structure, the low Dn and ΔHc/Hc were obtained. FePt–C30vol%(4 nm)/FePt–SiO245vol%(4 nm) film with Hc higher than 29 kOe and columnar FePt grains of 10 nm in diameter and 13 nm in height were obtained, which would be very suitable for heat assisted magnetic recording media.

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