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Superferromagnetism in Mechanically Alloyed fcc Fe23Cu77 with bimodal cluster size distribution
Authors: N. J. O. Silva, J. S. Amaral, V. S. Amaral , B. F.O. Costa, G. Le Caër
Ref.: J. Phys.: Condens. Matter 21, 046003-46012 (2009)
Abstract: Magnetic measurements, x-ray diffraction and Mossbauer spectroscopy were used to characterize a nanostructured fcc Fe23Cu77 at.% alloy prepared by high-energy ball-milling, addressing in particular the effect of clustering on the nature of the interacting magnetic entities. The interpretation of magnetization measurements leads to the conclusion that grains, whose mean size is similar to 16 nm, contain two populations of magnetic Fe-rich nanoclusters with a bimodal size distribution. These two sets of clusters contain about 14 and 400 Fe atoms and have magnetic moments of 30 mu(B) and 860 mu(B), respectively. The inter-cluster ferromagnetic interactions that lead to superferromagnetism with a Curie temperature T-C similar to 220 K can be described by a mean field determined by the smaller clusters only, which account for 90% of the magnetization.
