| Budget Amount *help |
¥2,900,000 (Direct Cost: ¥2,900,000)
Fiscal Year 2006: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2005: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Research Abstract |
We reported that the electric permeability ε_r' of ferromagnetic nanocomposite oxide sputtered films with a Bi2O_3-Fe_2O_3-PbTiO_3 ternary system is subject to change with an external magnetic field H (magnetocapacitance effect) and that electric polarization induced by a small ac magnetic field, ΔP_n(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 (p = 0.0016 Ωcm) 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 Δεr'(H) and 4πM_S.
We tried to measure Faraday spectra of the film applied electric field using the transmission type samples. Unfortunately, no signal was detected, since the multilayer film (ITO/magnetic film/ ITO) deposited on a heat-resistant glass substrate caused short circuit between electrodes after annealing. As a result, we presently plan to fabricate the reflection-type sample with a Si substrate and an ITO upper electrode.
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