Atomic composition effect on the ordering of solution-phase synthesized FePt nanoparticle films

Abstract

FePt nanoparticle monolayer films were fabricated with the nanoparticles stabilized on organic-coupling-layer coated Si substrates. The as-prepared films were nonmagnetic. In order to transform the nanoparticle phase from chemically disordered face-centered-cubic to chemically ordered L10, the films were annealed at 800°C under nitrogen atmosphere for 30min. The annealed films showed different degrees of sintering depending on the organic coupling layer materials used. At room temperature, sintered films exhibited high coercivity up to 2.4×104Oe, while monodispersive films with insignificant sintering showed a low coercivity of 1.1×102Oe. Such results can be explained by a large atomic composition distribution among the nanoparticles together with the size effect on ordering. Improvement of the nanoparticle atomic composition homogeneity is essential for applying the nanoparticle films for future ultrahigh-density data storage applications.