Novel synthesis of FePt nanoparticles and magnetic properties of their self-assembled superlattices

The novel synthesis of FePt nanoparticle superlattices by polyol reduction of platinum acetylacetonate and iron acetylacetonate is reported. The compositions of FePt nanoparticle are readily controlled, and the particle sizes are not significantly affected by the compositions, retaining to be ca. 3 nm with a very narrow size distribution. The FePt nanoparticles self-assemble into 2-D and 3-D superlattices. Thermal annealing converts the crystal structure of FePt nanoparticle from fee to L1₀ phase and transforms the superparamagnetic nanoparticle into ferromagnetic one.