Granular L1_0 FePt-X(X=C, TiO_2, Ta_2O_5) (001) nanocomposite films with small grain size for high density magnetic recording

摘要

FePt-X (X=C, TiO_2, Ta_2O_5) nanocomposite films were deposited on MgO/CrRu/glass substrates at 350 ℃ by magnetron cosputtering. The comparison investigations on the magnetic properties and microstructure of FePt-X films with various dopants were conducted. All FePt-X films showed (001) preferred orientation and oxide dopants promoted the formation of magnetically soft fcc FePt phase. With 15 vol % C doping, FePt-C film with columnar grains of 7.5 nm was obtained and the out-of-plane coercivity measured at room temperature was as high as 14.4 kOe. The increase in carbon volume fraction to 20% caused the formation of two-layer structure, whereas for the 20 vol % TiO_2 and Ta_2O_5 doping, the columnar structure of the FePt films remained and the corresponding grain sizes were 5 and 10 nm, respectively. Ta_2O_5 doping showed better grain isolation than the others. The out-of-plane coercivities of FePt-TiO_2 and FePt-Ta_2O_5 films were 7.5 and 8.8 kOe, respectively.