Nanoscale characterization of magnetic nanoparticles

A new technique for determining the magnetization direction of individual n anoparticles using the Foucault method of Lorentz microscopy is described E xperimental images for isolated SmCo5 nanoparticles as a function of the ob jective aperture shift direction are shown. In preparation for studies of i nterparticle coupling using this approach, preliminary results describing t he preparation of ordered arrays of magnetic nanoparticles are presented. H ere nonmagnetic nanorods of uniform size are shown to self-assemble into ar rays, which can be fixed in a silica matrix and heated to transform the rod s into a ferrimagnetic phase. (C)1999 Acta Metallurgica Inc.