1996 年 20 巻 2 号 p. 73-76
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.