Basic Study of Electric Field Induced Magnetization Reversal of Multiferroic (Bi_1-xBa_x)FeO₃ Thin Films at Room Temperature for Magnetic Recording Technology

抄録

  (Bi_1-xBa_x)FeO₃ multiferroic thin films with ferromagnetism and ferroelectricity were fabricated and applied to create magnetic recordings using an electric field. The (001)-oriented (Bi_1-xBa_x)FeO₃ thin films of which electric polarization direction is perpendicular to the film plane were fabricated onto a non-single-crystalline substrate with a Ta seedlayer / (111)-oriented Pt underlayer at a low substrate temperature of 500 ℃. A very high frequency plasma irradiation was applied during sputtering deposition of (Bi_1-xBa_x)FeO₃ to accelerate the crystallization at the low substrate temperature. The fabricated (Bi_0.6Ba_0.4)FeO₃ film exhibited hysteresis curves indicating ferromagnetic and ferroelectric behavior. The saturation magnetization of the film was approximately 60 emu/cm³ and the coercivity was approximately 2.5 kOe, respectively. Magnetic Force Microscopy analysis of the (Bi_0.6Ba_0.4)FeO₃ film confirmed that the magnetization was reversed by applying only a local electric field. The multiferroic film described here is expected to be useful for electric field-driven magnetic devices.