Materials World Network: Self-Assembled Nanocomposite Magnetoelectric Thin Films

该材料世界网络（MWN）项目是一项联合努力，开发具有强磁电耦合的自组装磁电（ME）纳米复合薄膜的新型低温湿化学处理方法。磁电效应被定义为外加磁场下介电极化的变化，或外加电场下感应磁化的存在。ME效应和材料具有丰富的基础科学和潜在的应用，如电可调谐磁微波器件、超灵敏磁场传感器、固态变压器等。具有铁电相和铁磁相/铁磁相的磁电复合材料与单相ME材料相比，具有强得多的ME耦合以及铁电相和铁磁相/铁磁相的特性可独立调谐的优点。ME薄膜对于CMOS/BICMOS或单片微波集成电路（MMIC）技术的应用至关重要。然而，大多数现有的合成ME复合材料的方法都是针对块状材料的，并且不能轻易地扩展到薄膜。在多层ME复合薄膜中，磁电耦合通常较弱，而在具有三维耦合微结构的纳米复合薄膜中，磁电耦合要强得多。到目前为止，关于ME纳米复合薄膜的研究还很有限。中国南京大学固体微结构国家实验室铁电材料组与东北大学微波磁性材料与集成电路中心的小组之间的合作努力构成了ME复合材料强度的强大协同配对。南京团队将开发一种溶胶-凝胶湿化学工艺制备三维耦合ME纳米复合薄膜；东北大学的团队将开发一种低温自旋喷雾湿式化学工艺来制备三维耦合ME纳米复合薄膜。南京小组将重点研究直流和亚mhz频率下的ME效应的表征；而东北组将专注于射频/微波频率的ME耦合。此外，东北组将用不同的技术在不同的长度尺度上对复合材料进行表征。南京研究组和东北研究组将共同建立对湿法合成ME纳米复合膜的工艺-结构-性能关系的认识。固态微结构国家实验室和微波磁性材料和集成电路中心之间的合作将为在CMOS/BICMOS和MMIC技术中利用ME薄膜以及尚未考虑的新器件和功能带来巨大的机会。同时，该MWN提案将使学生和初级研究人员积极参与国际研究经验。该奖项由国际科学与工程办公室东亚-太平洋项目共同资助。

This Materials World Network (MWN) project is a combined effort to develop novel low-temperature wet-chemical processing methods for self-assembled magnetoelectric (ME) nanocomposite films having strong ME coupling. The magnetoelectric effect is defined as the variation of dielectric polarization under an applied magnetic field, or the presence of an induced magnetization under an external electric field. The ME effect and materials are rich in both fundamental sciences and potential applications such as electrically tunable magnetic microwave devices, ultra-sensitive magnetic field sensors, solid state transformers, etc. Compared to single phase ME materials, magnetoelectric composite materials with ferroelectric and ferrimagnetic/ ferromagnetic phases have the advantages of much stronger ME coupling and the capability of independent tuning of the properties of the ferroelectric phase and the ferromagnetic/ferrimagnetic phase. ME films are essential for applications in CMOS/BICMOS, or monolithic microwave integrated circuits (MMIC) technologies. However, most of the available methods for synthesizing ME composites are for bulk materials, and cannot be readily extended to thin films. Magnetoelectric coupling is typically weak in multilayered ME composite films, whereas in nanocomposite films having 3-dimensional coupled microstructures the ME coupling is much stronger. Up until now, there has been limited published work on ME nanocomposite films. This collaborative effort between the ferroelectric materials group in the National Laboratory of Solid State Microstructures at Nanjing University, China, and the groups in Center for Microwave Magnetic Materials and Integrated Circuits at Northeastern University constitutes a strong, synergistic pairing of strength on ME composite materials. The Nanjing group will develop a sol-gel wet chemical process for 3-D coupled ME nanocomposite films; while the Northeastern groups will develop a low-temperature spin-spray wet chemical process for 3-D coupled ME nanocomposite films. The Nanjing group will focus on the characterization of the ME effects at DC and sub-MHz frequencies; while the Northeastern groups will focus on the ME coupling at RF/microwave frequencies. In addition, the Northeastern groups will characterize the composites at different length scales with different techniques. Together the Nanjing group and the Northeastern groups will establish the understanding on the processing- structure-property relationship in wet-chemical synthesized ME nanocomposite films. The proposed collaboration between the National Laboratory of Solid State Microstructures and the Center for Microwave Magnetic Materials and Integrated Circuits will lead to great opportunities for utilizing ME films in CMOS/BICMOS, and MMIC technologies, as well as novel devices and functionalities not yet considered. At the same time, this MWN proposal will enable active participation of students and junior researchers in international research experiences. This award is co-funded by the East Asia-Pacific Program of the Office of International Science and Engineering.