Magnetic After‐Effects in Iron‐Rich Ferrites Containing Vacancies

Abstract

Abstract Three ionic‐migration magnetic after‐effects are considered on the basis of a Fe 2+ ‐ion anisotropy model. These effects occur in magnetite, and in iron‐rich ferrites containing vacancies. A brief survey of experimental data is given. Results are quoted for temperature spectra of disaccommodation, domain‐wall stabilization in polycrystalline samples, and induced anisotropy relaxation in single crystals. All three effects can be ascribed, by using Slonczewski's theory, to the Fe 2+ anisotropic interaction with the spontaneous magnetization in a spinel lattice. It is believed that this interaction causes migration of single Fe 2+ ‐ions, and of Fe 2+ — Fe 2+ pairs, through intermediary single vacancies. Satisfactory qualitative agreement is found between the experimental results and the proposed model.