Control of magnetization in spinel-type Fe sub(3)O sub(4) thin films by N sub(2) ion implantation

The magnetism of a typical spinel ferromagnetic oxide, Fe sub(3)O sub(4), was controlled via ion implantation. Nitrogen ions were accelerated at 6-10 kV and irradiated to the 13-nm-thick Fe sub(3)O sub(4) thin films with dosages of 2 x 10 super(16) to 6 x 10 super(16) ions/cm super(2). The magnetization decreased with the increase in ion dosage, and there was almost no magnetization when 6 x 10 super(16) ions/cm super(2) of nitrogen was irradiated, irrespective of the acceleration voltages. The results of the temperature dependence of the magnetization and the Mossbauer study suggest that the transition from ferromagnetic to nonmagnetic phases in the Fe sub(3)O sub(4) thin film upon N sub(2) ion irradiation proceeds abruptly without the formation of intermediate states.