外界激励下多铁性层状磁电复合薄膜非线性磁电效应的研究

Multiferroic materials can be used in new type of magnetoelectric sensors, spintronic devices, new information storage devices and other fields, which has become one of the most noteworthy research field. In recent years, the miniaturization, integration, low power consumption of the magnetoelectric components has prompted multiferroic magnetoelectric composites from the development of bulk materials to the thin films. For the intelligent devices and the self-driven system based on magnetoelectric composite thin films, it is essential to establish theoretical model to quantitatively describe the relationship between input and output of the mechanics, electric and magnetic. This research will firstly study the size effect, flexoelectric effect, and dynamic multi-fields coupling and nonlinear mechanical characteristics of the multiferroic layered magnetoelectric composite thin films, then carry out numerical simulation on composite thin films or structures using non-piezoelectric materials and functionally graded materials, effectively characterizing the change law of magnetoelectric coefficient with the external excitations, physical dimension, strain gradient and the type of the material gradation. This study will provide micro-nano scale magnetoelectric coupling mechanism with different advanced characterization means and methods, and offer a theoretical reference for the development and application of magnetic-mechanical-thermal-electric coupling nonlinear micro/nano intelligent devices.

多铁性材料可用于新型磁电传感器件、自旋电子器件、新型信息存储器件等领域，目前已成为国际上最值得关注的热点研究领域之一。近年来，元器件的微型化、集成化、低功耗的需求促使多铁性磁电复合材料的研究从块体材料向薄膜发展。对于采用磁电复合薄膜材料的智能器件和自驱动系统来说，建立可以定量描述力学、电学、磁学输入量与输出量之间关系的理论模型是必不可少的。本项目将展开对多铁性层状磁电复合薄膜的尺寸效应、挠曲电效应、动态多场耦合非线性力学特征的研究，并针对采用非压电材料和功能梯度材料的复合薄膜材料或结构进行数值模拟和仿真，有效表征其磁电系数随着外界激励、结构尺寸、应变梯度及材料性能分布形式的变化规律。本项目的研究将为微纳尺度上磁电耦合机制提供不同先进表征手段和方法，相关成果可为磁-力-热-电相互关联和控制的非线性微纳米智能器件的开发与应用提供理论参考。

本项目首先展开对多铁性层状磁电复合薄膜的尺寸效应、动态多场耦合非线性力学特征的研究，建立了可以定量描述和评估微纳磁电结构与器件性能的理论模型，预测了磁电耦合的尺寸依赖性，揭示了外界激励对结构等效弹性性能、磁电系数以及共振频率等的非线性作用，提出了调节磁电耦合强度的方法。其次，基于组份材料的挠曲效应，发展了挠曲磁电效应理论框架。揭示了外界激励、应变梯度和极化电场之间的相互耦合机制，通过研究微纳结构中挠曲磁电耦合和压磁电耦合的竞争关系，论证了不采用任何压电和压磁材料设计磁电结构的设想。基于所提出的理论模型，开展了新型磁电结构的设计和实验测试。提出了一种扭振磁电耦合器件和基于Terfenol-D材料的光纤磁场传感器，并对其性能进行了有效预测。实验测试了一种典型磁电结构在不同磁场加载模式下的材料参数，报道了磁电双峰现象等非线性行为。本项目的研究将为微纳尺度上磁电耦合机制提供不同先进表征手段和方法，相关成果可为磁-力-热-电相互关联和控制的非线性微纳米智能器件的开发与应用提供理论参考。