Magnetic-Field-Induced Electric Polarization in Iron-Based Ferromagnetic Oxide Sputtered Films.
Magnetic-Field-Induced Electric Polarization in Iron-Based Ferromagnetic Oxide Sputtered Films.
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铁基铁磁氧化物溅射薄膜中的磁场感应电极化。
DOI：
10.3379/jmsjmag.27.348
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发表时间：
2003
影响因子：
--
通讯作者：
T. Fujii
中科院分区：
文献类型：
--
作者：
A. Kajima;R. Nakayama;T. Ohashi;M. Inoue;T. Fujii
在我们以前的论文中，已经报道了具有Bi2O3Fe2O3PbTiO3三元系的铁磁纳米复合氧化物薄膜的介电常数Er‘随磁场H，ΔEr’(H)的变化。在本研究中，我们首先测量了Er‘和ΔEr’(H)的温度依赖性。这两个量在50°C以上迅速增加，这表明在此温度下介电基质的玻璃网络发生软化，以促进引起介电极化的电荷位移。接下来，我们测量了位移电流JD(H)的磁场依赖关系，以确认磁导率随磁场ΔEr‘(H)的变化是否为本征。结果表明，Jd(H)的变化规律与ΔEr‘(H)的变化规律相似，说明确实发生了H辅助的电荷位移。最后，我们观察到在室温下施加一个小的交流磁场所引起的介电极化。这被认为是一种新型的电磁效应。为了解释实验结果，我们提出了一个基于分散在介电玻璃基质中的铁磁纳米团簇的磁化旋转的简单模型。
In our previous papers, it was reported that the dielectric permeability er' is subject to change with magnetic field H, Δer'(H) in ferromagnetic nano-composite oxide films with the Bi2O3-Fe2O3-PbTiO3 ternary system. In the present study, we first measured the temperature dependence of er' and Δer'(H). Both quantities increase rapidly above 50°C, 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 Jd(H) to confirm whether the permeability change with magnetic field Δer'(H) is intrinsic. It was found that Jd(H) is also subject to change in a similar manner to Δer'(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.