鉄基強磁性酸化物スパッタ薄膜における磁界誘導電気分極(薄膜)

概要

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In our previous papers, it was reported that the dielectric permeability ε_r' is subject to change with magnetic field H, Δε_r'(H) in ferromagnetic nano-composite oxide films with the Bi_2O_3-Fe_2O_3-PbTiO_3 ternary system. In the present study, we first measured the temperature dependence of ε_r' and Δε_r'(H). Both quantities increase rapidly above 50℃, which suggests that softening of the glass network of the dielectric matrix takes place at this temperature to promote the charge displacement giving rise to the dielectric polarization. Next, we measured the magnetic field dependence of the displacement current J_d(H) to confirm whether the permeability change with magnetic field Δε_r'(H) is intrinsic. It was found that J_d(H) is also subject to change in a similar manner to Δε_r'(H), indicating that the charge displacement assisted by H really occurs. Finally, we observed the dielectric polarization induced by applying a small ac magnetic field at room temperature. This is considered to be a new type of electromagnetic effect. To explain the experimental results, we propose a simple model based on magnetization rotation of ferromagnetic nano-clusters dispersed in a dielectric glassy matrix.
社団法人日本磁気学会の論文
2003-04-01