Co-Deposition of FePt and FePt/Ag Nanoparticles on Silicon Dioxide

摘要

The urgent need in recent years for higher information storage density has led to a strong interest on magnetic nanostructures. FePt nanoparticles are excellent candidates for high-density recording media, because the high anisotropy constant of their tetragonal form enables them to avoid the superparamagnetic behavior, even for particles of few nanometers in diameter [1]. Furthermore, the growth and the investigation of FePt nanoparticles on SiO{sub}2/Si substrates can be interesting not only in the field of high density recording media but as a possible implementation of FePt nanoparticles in future integrated circuitry. However, the structural ordering of ferromagnetic FePt nanoparticles in the high anisotropy phase exhibit two limitations for technological applications. The high temperatures necessary to obtain the L1{sub}0 ordered structure and the surface effects on the ordering, whose extent increases with decreasing the nanoparticle size. In order to reduce the activation energy for the ordering of FePt nanoparticles, Ag layers or seeds have been used for thin films [2] or self-assembled [3] nanoparticles respectively. For these reasons, the aim of the present study is to deposit FePt nanoparticles on SiO{sub}2/Si substrates using Ag nuclei to investigate their crystallographic, morphological and magnetic effects on the alloy nanoparticles, and consequently, the enhancement of their coercivities.