Preparation and magnetic properties of size-monodispersed Fe-Co alloy nanoclusters

Fe₇₀Co₃₀ alloy clusters were prepared by a plasma-gas-condensation-type cluster deposition technique. By adjusting the deposition parameters, size-monodispersed Fe₇₀Co₃₀ alloy clusters were obtained and their average sizes can be changed from 8.6 to 14.3 nm. The structural and magnetic properties of these alloy nanoclusters were studied. The as-obtained Fe₇₀Co₃₀ clusters have a body-centered-cubic alpha-(Fe,Co) structure although a very weak oxide phase ((Fe,Co)₃O₄ or gamma-(Fe,Co)₂O₃) was also detected because the cluster assemblies have to be exposed to the ambient atmosphere for transmission electron microscopy (TEM) observation and magnetic measurement. Based upon the magnetic measurement results, we compared and discussed the magnetic differences between Fe₇₀Co₃₀ alloy clusters and pure Fe and Co clusters.