Layer-by-Layer Assembly of Core-Shell Magnetite Nanoparticles: Effect of Silica Coating on Interparticle Interactions and Magnetic Properties

Farkhad G. Aliev, Miguel A. Correa-Duarte, Arif Mamedov, John W. Ostrander, Michael Giersig, Luis M. Liz-Marzán, and Nicholas A. Kotov

Adv. Mat., 1999, 11, 1006–1010

Layered magnetic materials have been prepared using layer-by-layer deposition, a technique that allows engineering of the structure of individual particles while remaining simple to carry out. Organic–inorganic sandwich films of superparamagnetic Fe3O4 thus prepared consisted of densely packed assemblies of Fe3O4 nanocrystallites that showed good adhesion to a variety of substrates and excellent mechanical properties. Coating the nanoparticles with a shell of SiO2 was found to greatly reduce the cooperative magnetization switching between adjacent nanoparticles.