On magnetically induced orientation and self-organization in ferrofluids

Magnetic field-induced anisotropy of diluted ferrofluid γ-Fe2O3 has been studied by optical and magnetic resonance methods. The angular and field dependences obtained in the optical experiments were found to be similar to those obtained by electron magnetic resonance. It was shown that the model accounting for an individual nanoparticle anisotropy as a main source of the field-induced anisotropy does not describe experimental data, and the formation of chains through dipole-dipole interaction must be taken into account.