Structural and magnetic properties of monolayer film of CoPt nanoparticles synthesized by polyol process.

Co₄₃Pt₅₇ nanoparticle dispersion was synthesized by using the polyol process, and monolayer film of the particles with [3-(2-aminoethylamino)propyl]trimethoxysilane coupling layer on a silicon substrate was fabricated and characterized. After the film was annealed at 873 K, the Co₄₃Pt₅₇ nanoparticles transformed from their as-deposited fcc phase to L10 structure. However, the resulting c/a ratio was only 0.993, indicating incomplete transformation. Grain size of the annealed film was 4.9 nm against 4.1 nm for the as-deposited state. The annealed film showed the presence of high anisotropic phase with the remanence coercivity of 4.2 kOe and anisotropy field over 25 kOe at RT. [ABSTRACT FROM AUTHOR]