Nanocomposite L10 FePt–SiNx and FePt–SiNx–C films with large coercivity and small grain size on a TiN intermediate layer

Abstract FePt–SiN x –C films with high coercivity, (001) texture and small grain size were obtained by co-sputtering FePt, Si 3 N 4 and C on TiN/CrRu/glass substrate at 380 °C. Without C doping, FePt–SiN x films with good perpendicular anisotropy and a single layer structure were obtained. However, the grain size was still too large and the grain isolation was poor. When C was doped into the FePt–SiN x films, the out-of-plane coercivity increased due to the decrease of the exchange coupling. In addition, the grain size of the FePt films decreased, and well-separated FePt grains with uniform size were formed. The microstructure of [FePt–SiN x  40 vol%]−20 vol% C films changed from a single layer structure to a multiple layer structure when the FePt thickness was increased from 4 to 10 nm. By optimizing the sputtering process, the [FePt (4 nm)–SiN x 40 vol%]−20 vol% C (001) film with coercivity higher than 21.5 kOe, a single layer structure, and small average FePt grain size of 5.6 nm was obtained, which makes it suitable for ultrahigh density perpendicular recording.