Abstract
Fe clusters have been synthesised in ultra-high-vacuum chamber using a gas-stabilized cluster aggregation method that ensures good control of the cluster size and naturally oxidized in order to obtain Fe/Fe oxide core-shell nanoparticles. The morphology of an individual nanoparticle, as revealed by transmission electron microscopy, consists of a Fe core of an average diameter of 4.4 nm surrounded by an oxide shell of uniform thickness of about 1.2 nm in average. The nanoparticles may be assimilated with a ferro-/antiferromagnetic (FM/AF) system. The morpho-structural features have been correlated with magnetic measurements on the core-shell nanoparticles. A significant exchange bias effect has been measured, when the sample was field-cooled under an applied field of 3 T. As the morphology of core-shell nanoclusters is much more complicated than in FM/AF bilayers of regular thickness due to the particular geometry of the coronal AF layer, the shape and surface anisotropy have to be taken into account for a correct interpretation of the magnetic data.
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Acknowledgements
Part of the work has been financially supported by the Romanian Ministry of Research under the research projects CEEX 20/2005 and PNCDI II 71-060/2007. This work was also supported by the EPSRC and EU project NANOSPIN.
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Crisan, O., von Haeften, K., Ellis, A.M. et al. Structure and magnetic properties of Fe/Fe oxide clusters. J Nanopart Res 10 (Suppl 1), 193–199 (2008). https://doi.org/10.1007/s11051-008-9463-3
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DOI: https://doi.org/10.1007/s11051-008-9463-3