Effect of functionalization on positional ordering of 3Â nm FePt nanoparticles: Langmuir-Blodgett monolayer

Surface functionalization of nanoparticles helps to tailor positional ordering of FePt nanoparticles which is essential for potential application for density media recording. The FePt nanoparticles were synthesized using the chemical method. The size of the as synthesized monodispersed FePt nanoparticles was estimated to be ~ 3 nm using TEM. Structural and magnetic phase transitions from a disordered face centered cubic to chemically ordered face centered tetragonal phase with a hard magnetic behavior were observed on heat treatment. The FePt nanoparticles prepared chemically were further coated with oleylamine, 11-mercaptoundecanoic acid (11-MUA) and stearic acid. The Langmuir-Blodgett monolayer depositions were carried out using functionalized FePt nanoparticles. The pressure-area (π-A) isotherm measurements were used to identify the appropriate pressure for the deposition of the monolayers on the substrates. TEM results show the long range positional ordering of micrometer range only for the amine functionalized FePt nanoparticles.