Magnetic properties of fine maghemite particles in an electroconducting polymer matrix

Abstract The magnetic properties of γ - Fe 2 O 3 grains of a few nanometers in size, included in films of conducting polypyrrole by electrochemical synthesis, are investigated. A theoretical treatment of the combined effects of the possible non-uniform spontaneous magnetization of the grains and of their crystalline anisotropy energies is presented. The magnetization of samples of this composite material has been measured at several temperatures as a function of the field up to 30 kOe. The interpretation of these data shows that the grains in the polymer behave as independent monodomains, coexist with the polymer without any notable interference, and have the same size distribution as in the ferrofluid solution used for the electrochemical inclusion.