The preparation of ordered colloidal magnetic particles by magnetophoreticdeposition

The preparation of ordered two-dimensional (2D) magnetic nanoparticles usin g a magnetophoretic technique is reported. The quality of the ordering can be observed by electron microscopy and the lattice constants determined by electron diffraction. Using image processing it can be shown that the cobal t particles condense into a hexagonal close packed array, and that the crys tallographic axes of the individual cobalt particles are randomly oriented. Furthermore, the equilibrium distance between the 2D ordered particles dec reases with increasing strength of the magnetic field while the minimum dis tance corresponds approximately to the size of the adsorbed stabilizers. Th e method is of general interest as a means of preparing monolayer films of nanosized magnetic particles such as cobalt or iron oxide.