Synthesis of ${\rm L}1_{0}$ (FePt) $_{100{-}{\rm X}}$ -Au

A monolayer of L1₀ FePt nanoparticles was fabricated on a polymer film by introducing a Au seed layer prior to the Fe-Pt deposition on the polyimide film. The particle size distribution was tightened from 5.1plusmn1.8 nm to 3.8plusmn1.1 nm by introducing the Au seeds to induce a preferential nucleation of the deposited metal on the preexisting Au particles. Deposition and annealing was repeated so that well-separated hard magnetic nanoparticles with several nanometers in diameter were achieved in a monolayer configuration. The method can be easily extended to a larger area as well as to other alloy systems to create a monolayer of nanoisland structures on a polymer film.