鉄基強磁性酸化物薄膜における電気磁気相互作用 : 下地基板の影響と温度特性(薄膜)

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We previously reported that the electric permeability ε_r' of ferromagnetic nanocomposite oxide sputtered films with a Bi_2O_3-Fe_2O_3-PbTiO_3 ternary system is subject to change with an external magnetic field H and that electric polarization induced by a small ac magnetic field, ΔP_h(ω), is observed. To explain these experimental results, we proposed a model based on magnetization rotation of ferromagnetic nanoclusters dispersed in a dielectric matrix. However, it was found that, when Si-wafers are used as substrates, a depletion layer attributed to the MIS structure is formed in the film-to-Si interface, which seriously affects measurements of the magnetic-field-sensitive portion of the permeability Δε_r'(H). In order to eliminate this completely, we used heavily doped n^+-Si wafers (ρ=0.0016Ωcm) as substrates, by which means we were able to obtain accurate Δε_r'(H)-value for a wide range of frequencies. In addition, we measured the temperature dependence of Δε_r'(H) and the saturation magnetization, 4πM_s, of a film to seek for the mechanism of this electromagnetic effect, as a result of which a close correlation was found to exist between Δε_r'(H) and 4πM_s.
社団法人日本磁気学会の論文
2006-03-01