Mechanics of Multiferroic Composites for Strong Magnetoelectric Coupling

这个项目的目标是通过由铁电和铁磁组成的多铁复合材料的路线寻求尽可能强的磁电耦合。这种想法源于这样一种认识，即单相多铁材料是罕见的，在现有的材料中，它们的磁电耦合通常很弱。另一方面，多铁性复合材料可以通过它们共同的机械特性提供强大的磁电相互作用。在这项研究中，我们将通过微观力学和相场相结合的方法来探索块体和纳米结构多铁复合材料的最大潜力。我们将应用开发的复合模型来调整它们的体积浓度、相连通性和性质对比，以实现这一目标。通过测定复合材料在外加磁场作用下的总极化和在外加电场作用下的总磁化强度来评估磁电耦合。在这个过程中，铁电和磁畴的演化也将被揭示。我们打算更详细地考虑BaTiO_3-CoFe_2O_4复合材料，体相为1-3，2-2，0-3和3-3，纳米结构薄膜为1-3和2-2。通过这种方式，可以量化每个连接图案和所有图案的最大磁电耦合。具有强磁电耦合的多铁性材料具有广泛的应用，需要机械能、电能和磁能的交换和相互作用。例如，在信息存储中，耦合允许数据以电子方式写入和以磁性方式读取，从而避免需要创建高局部磁场来写入。众所周知，这类材料还可用作执行器、传感器、换能器和高频设备，这些设备的性能需要通过电气或磁性进行调节。在微电子领域，片上集成也要求使用许多纳米级的多铁性材料。这项工作将对新的高端设备的开发产生直接影响。我们打算利用这个机会培养一些高中生、本科生和研究生。PI将与TARGET(罗格斯大学工程与技术女孩学院)建立一个暑期计划，以提高她们的意识。他将招募有动力的本科生加入荣誉J.J.斯莱德奖学金计划(需要一篇论文)，并通过一门新课程-多铁性材料力学-为研究生提供多学科培训，并每周举行研讨会。积极招收少数民族、女性和经济困难学生。结果将通过出版物、讲座和网站向公众开放。

The goal of this project is to seek the strongest possible magnetoelectric coupling through the route of multiferroic composites that consist of a ferroelectric and a ferromagnetic phase. This idea grew out of the realization that single-phase multiferroic materials are rare, and among the existing ones their magnetoelectric coupling is generally weak. On the other hand a multiferroic composite could deliver strong magneto-electric interactions through their commonly shared mechanical characteristics. In this research, we will explore the maximum potential through a combination of micromechanics and phase-field approaches for both bulk and nanostructured multiferroic composites. We will apply the developed composite models to tune their volume concentrations, phase connectivity, and property contrast, to achieve this goal. The overall polarization of the composite under an external magnetic field, and its overall magnetization under an external electric field, will be determined to assess the magnetoelectric coupling. In this process the evolution of ferroelectric and magnetic domains will also be uncovered. We intend to consider BaTiO3-CoFe2O4 composites in great details, with the 1-3, 2-2, 0-3, and 3-3 connectivity for the bulk, and 1-3 and 2-2 for nanostructured thin films. In this way the maximum magnetoelectric coupling for each connectivity pattern, and for all patterns, can be quantified. Multiferroic materials with strong magnetoelectric coupling have a wide range of applications that require the exchange and interaction of mechanical, electrical, and magnetic energies. In information storage, for instance, coupling allows the data to be written electronically and read magnetically, thus avoiding the need to create a high local magnetic field to write. This class of materials is also widely known to be useful as actuators, sensors, transducers, and high-frequency devices whose properties need to be tuned electrically or magnetically. In microelectronics, the on-chip integration also demands the use of many nano-scaled multiferroics. This work will have direct impact to the development of new high-end devices. We intend to use this opportunity to educate some high school and undergraduate and graduate students. The PI will establish a summer program with TARGET (The Academy at Rutgers for Girls in Engineering and Technology) to increase their awareness. He will enlist the motivated undergraduates to join the Honor J.J. Slade Scholar Program (which requires a thesis), and provide multidiscipline training to the graduate students with a new course, Mechanics of Multiferroic Materials, and a weekly seminar. Minority, women, and economically underprivileged students will be actively recruited. The results will be made open to the public through publications, lectures, and a website.