Magnetic properties of Sb-doped FePt nanoparticles

Abstract

Sb-doped FePt nanoparticles with an average diameter of 8.5 nm were prepared by thermal

decomposition of platinum acetylacetonate, antimony acetate, and iron pentacarbonyl. Upon

annealing to ~300°C for 30 min, nanoparticles with XSb=0.14 and 0.23 show Hc>500 mT, and

L10 ordering parameter S values of ~0.83–0.87. Transmission electron microscopy of the annealed

assemblies shows no observable nanoparticle coalescence at 300°C. Low-temperature coercivity

measurements with a superconducting quantum interference device indicate the presence of

particles that exhibit superparamagnetism, probably due to the large particle size distribution or

inhomogeneity in Sb incorporation. Our results underscore the necessity to synthesize monodisperse

FePt nanoparticles with controlled composition to maximize ferromagnetic behavior.