Ultrasmall iron nanoparticles : effect of size reduction on anisotropy and magnetization

Stable iron nanoparticles have been synthesised by the decomposition of {Fe (N [Si (C H3)3] 2)2 }2 under dihydrogen pressure. Those conditions lead to a system of monodisperse and metallic nanoparticles which diameter is less than 2 nm and stabilized by HN [Si (C H3)3] 2. The magnetization is found to be MS =1.92 \u3bcB at., i.e., 10% lower than the bulk value. The M\uf6ssbauer spectrum is fitted by two contributions of metallic iron. The magnetic anisotropy energy constant increases up to 5.2 7 105 J m3, i.e., ten times the bulk one