Synthesis of FePt and FePtCu Nanoparticles by a Reverse Micelle Method and Studies of Magnetic Recording Media Using Them

Nanoparticulate FePt, which is highly stable under heating, is a very promising magnetic material for future super-highdensity magnetic recording media. The FePt and FePtCu nanoparticles were synthesized by a reverse micelle method (H2O/sodium bis (2-ethylhexyl) sulfosuccinate (AOT)/decane). FePt and FePtCu nanoparticles obtained with this method exhibited monodispersity and homogeneous elemental composition (both coefficients of variation are less than 10%), and the average diameter of these particles was able to arbitrarily controlled between 3 and 9 nm. Further, annealing of the FePtCu nanoparticles in an Ar+H2 (5%) gas lowered the temperature for modification from fcc to fct by way of the oxidation state to the range of 350°C-375°C. Nanoparticulate FePt and FePtCu media coated on glass substrates had a surface roughness (Ra) of less than 1 nm and showed magnetic recording capability.