1-3型纳米多铁复合薄膜中电场诱导的磁化研究

运用Landau-Devonshire热力学唯像理论，考虑铁电相和铁磁相的电致伸缩、磁致伸缩效应以及产生于铁电/铁磁和薄膜/基底界面的弹性应力作用，两次重整介电和磁作用系数得到了这种多铁系统在Landau自由能函数下的本征二次方磁电耦合形式，从而研究了外延1-3型纳米多铁复合薄膜中极化、磁化随薄膜厚度、温度的变化以及该薄膜中外加电场诱导的磁化变化.结果表明薄膜平面内的应压力的弛豫使得磁化强度和极化强度随薄膜厚度的增加而减少，外加电场不仅能诱导铁电相极化场翻转，而且由于铁电和铁磁相界面竖直方向的弹性耦合导致 关键词： 多铁 磁电效应 磁致伸缩 薄膜

Electric-field-induced magnetization in 1-3 type multiferroic nanocomposite thin film

Considering the electrostrictive，magnetostrictive effects in the ferroelectric （FE） phase and ferromagnetic （FM） phase and the elastic stress arising from FE/FM and film/substrate interfaces，using the Landau-Devonshire thermodynamic theory，we investigate the magnetoelectric coupling effect in epitaxial 1-3 type multiferroic nanocomposite thin films. We renormalize the dielectric and magnetic coeffcients twice and obtain the quasi-intrinsic magnetoelectric coupling in Landau free energy function of this multiferroic system. Then，the electrical-field-induced magnetization and polarization for films of different thickness in 1-3 type BaTiO₃-CoFe₂O₄ nanocomposite system are analyzed. Our results show that the relaxation of the in-plane compressive stress of the thin film makes magnetization and polarization both decrease with the increasing film thickness，and an applied electric field can result in the reversal of magnetization in step with the switching of the electric polarization due to the out-of-plane elastic coupling between the interface of the FE and FM phases. Our results agree well with the experimental results.