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

Stable iron nanoparticles have been synthesised by the decomposition of {Fe(N[Si(CH3)(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(CH3)(3)](2). The magnetization is found to be M-S=1.92 mu(B)/at., i.e., 10% lower than the bulk value. The Mossbauer spectrum is fitted by two contributions of metallic iron. The magnetic anisotropy energy constant increases up to 5.2x10(5) J/m(3), i.e., ten times the bulk one.