SGER: Multiferroic Materials Based on Polymer-Metal Salt Composites

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TECHNICAL SUMMARY:This proposal describes the study of a new class of flexible multiferroic materials based on polymer/metal salt composites. Multiferroics, which are rare materials, simultaneously exhibit ferroelectricity (capable of maintaining a permanent electric moment) and ferromagnetism (capable of maintaining a permanent magnetic moment). The polymer portion of the composite is based on poly(vinylidene difluoride) (PVDF), which is well known to be a ferroelectric material. Adding small amounts of paramagnetic salts provides the magnetic component. When the metal salt is at concentrations less than 1 % by mass the composite material demonstrates ferromagnetism. Such behavior in polymer/ionic salt composites is unprecedented and promises to reveal new physics and chemistry in this class of materials. Fundamental questions to be addressed include: what is the mechanism of magnetic coupling in these dilute spin systems? Does aggregation play a role? What are the characteristics of the magnetoelectric coupling between the electric moment and the magnetic moment? How can these properties be changed by modifying the chemistry of the composite? New materials will be made composed of a variety of paramagnetic transition metal salts (including Cr3+, Mn2+, Fe2+, Fe3+, Co2+, and Cu2+) at several concentrations. Each new composite will be characterized by a comprehensive set of structural, spectroscopic, magnetic, and electrical experiments.NON-TECHNICAL SUMMARY:The multiferroic nature of the new materials is expected to lead to new physics associated with the magnetoelectric coupling and to new types of applications. Devices that could be constructed from multiferroics include multiple-state memory elements, reconfigurable antenna elements, advanced sensors, negative index media, and microelectromechanical actuators. Since the composites are based on a polymer matrix, these new devices can be thin films, flexible, or moldable. In addition to addressing a key national need, the project will enhance graduate and undergraduate education by providing a highly multidisciplinary project. The research will be done in collaboration with researchers at Hanscom Air Force Base, which will provide the participating students exposure to scientists and engineers from outside the academic realm. Certain aspects of the research activities are within reach of high school students so pre-college students will be recruited from local high schools to participate, with a special emphasis on targeting minority and underrepresented groups.