Materials World Network: Self-Assembled Nanocomposite Magnetoelectric Thin Films

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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.