NiO 下地膜上の Co-γFe₂O₃ 垂直磁化膜の作製と磁気特性

抄録

NiO underlayer with a <100> orientation were prepared on a glass substrate by reactive rf sputtering at ambient temperature. Fe₃O₄ and CoO multilayers were grown epitaxially on the underlayer at 200°C; the Fe₃O₄ and CoO on the NiO underlayer grew along the <100> axis irrespective of the bilayer thickness. <100> oriented Co-γFe₂O₃ films [Co-γFe₂O₃/NiO] with perpendicular magnetic anisotropy were obtained after annealing of the multilayers in air at 280-350°C. The squareness ratio compensated by a demagnetization coefficient and the anisotropy energy of Co-γFe₂O₃/NiO were 0.94 and 1.4 × 10⁶erg/cm³, respectively; these values were larger than those of the CoγFe₂O₃ on the glass substrate (0.85 and 1.1 × 10⁶erg/cm³, respectively). The coercivity of CoγFe₂O₃/NiO increased with the Co content and could be controlled in the region of 0.8-5.0 kOe.