Stolbov Oleg V, Raikher Yuriy L
Laboratory of Dynamics of Disperse Media, Institute of Continuous Media Mechanics, Russian Academy of Sciences, Ural Branch, 614018 Perm, Russia.
Nanomaterials (Basel). 2025 Mar 25;15(7):487. doi: 10.3390/nano15070487.
Numerical modeling of the direct magnetoelectric (ME) effect in a PVDF-cobalt ferrite (CFO) composite film has been performed. The problem is solved within the framework of the mesoscopic RVE approach, where each elementary cell contains three particles with varying mutual positions. Both modes of mechanical stress generation are taken into account: magnetostrictive and magnetorotational, i.e., changes in the shape and rotation of the particle as a whole. Depending on the sign of the magnetostriction constants, these sources of piezopolarization can either enhance or reduce the overall ME effect. A significant dependence of the ME effect on the mutual arrangement of CFO particles in the cell has been discovered; for instance, the effect is minimal when the particles are closest to each other. In other words, clustering is a negative factor. In a system where the magnetic moments of the magnetically hard CFO particles are ordered, the maximum ME effect is attained when the poling direction is at an angle of about 40∘ to the film plane. As it turns out, a fairly good estimate of this angle can be obtained from the solution of a single-particle problem; the main contribution here comes from the 'diagonal' components of the piezotensor: d31 and d33. The 'tangential' component d15 plays a special role: changing its sign can reverse the polarity of the charge generated on the film.
已对聚偏氟乙烯-钴铁氧体（CFO）复合薄膜中的直接磁电（ME）效应进行了数值模拟。该问题是在细观代表性体积单元（RVE）方法的框架内解决的，其中每个基本单元包含三个相互位置不同的粒子。考虑了两种机械应力产生模式：磁致伸缩和磁旋转，即粒子整体形状和旋转的变化。根据磁致伸缩常数的符号，这些压电极化源可以增强或降低整体磁电效应。已发现磁电效应强烈依赖于单元中CFO粒子的相互排列；例如，当粒子彼此最接近时，效应最小。换句话说，聚集是一个负面因素。在硬磁CFO粒子的磁矩有序排列的系统中，当极化方向与薄膜平面成约40°角时，可获得最大磁电效应。事实证明，从单粒子问题的解中可以得到对该角度的相当好的估计；这里的主要贡献来自于压电张量的“对角”分量：d31和d33。“切向”分量d15起着特殊作用：改变其符号可以使薄膜上产生的电荷极性反转。
