Control of magnetization in spinel-type Fe3O4 thin films by N2 ion implantation

Abstract

The magnetism of a typical spinel ferromagnetic oxide, Fe3O4, was controlled via ion implantation. Nitrogen ions were accelerated at 6–10 kV and irradiated to the 13-nm-thick Fe3O4 thin films with dosages of 2 × 1016 to 6 × 1016 ions/cm2. The magnetization decreased with the increase in ion dosage, and there was almost no magnetization when 6 × 1016 ions/cm2 of nitrogen was irradiated, irrespective of the acceleration voltages. The results of the temperature dependence of the magnetization and the Mössbauer study suggest that the transition from ferromagnetic to nonmagnetic phases in the Fe3O4 thin film upon N2 ion irradiation proceeds abruptly without the formation of intermediate states.