Magnetization control for bit pattern formation of spinel ferromagnetic oxides by Kr ion implantation

概要

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As a first step toward the development of bit-patterned magnetic media made of oxides, we investigated the effectiveness of magnetism control by Kr implantation in a typical spinel ferromagnetic oxide, Fe3O4. We implanted Kr ions accelerated at 30 kV on 13-nm-thick Fe3O4 thin films at dosages of (1–40) × 1014 ions/cm2. Magnetization decreased with increase in ion dosages and disappeared when irradiation was greater than 2 × 1015 ions/cm2 of Kr ions. These dosages are more than ten times smaller than that used in the N2 implantation for metallic and oxide ferromagnets. Both the temperature dependence of magnetization and the Mössbauer study suggest that the transition of Fe3O4 from ferromagnetic to paramagnetic took place sharply due to Kr ion irradiation, which produces two-phase separation—ferromagnetic and nonmagnetic with insufficient dosage of Kr ions.
American Institute of Physicsの論文