Materials and Mechanisms of Multiferroicity

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**Non-Technical Abstract**Magnetism and ferroelectricity are imperative bases for current technology and the quest for multiferroic materials is of great technological and fundamental importance. The significant cross-coupling effects between magnetism and ferroelectricity tend to occur at low temperatures--far below room temperature. To discover new multiferroics with enhanced cross-coupling effects at room temperature, and consequently to exploit tunable multifunctional devices with multiferroics, the project will investigate the microscopic origin of multiferroicity, attempt to unveil the dynamics relevant to the coupling effects, and explore new materials. The proposed studies will have a significant impact not only on specific issues in the field of multiferroics but also on a broad class of multifunctional complex materials, where lattice structuring plays an essential role in electronic and magnetic properties. The centerpiece of the proposal is a wide spectrum of collaboration, so a multiplicity of techniques and skills will be utilized. The proposed study will further strengthen the role of research in all levels of education. For example, high school students will be involved in the proposed research through the Partners in Science program, organized by the Liberty Science Center, Jersey City, New Jersey, which the PI has continuously involved in for the last 10 years.**Technical Abstract**These projects focus on exploring new materials and understanding mechanisms of multiferroics, where magnetism and ferroelectricity coexist and can be cross-coupled to each other. The spin-lattice coupling, which is the ultimate driving force for the novel effects in multiferroics, is often relatively weak in these compounds. In addition, the critical temperature, Tc, below which couplings of various degrees of freedom take place is frequently well below room temperature. In order to discover new multiferroics with enhanced cross-coupling effects and Tc, and consequently to exploit tunable multifunctional devices with multiferroics, this project will attempt to connect multiferroicity with microscopic spin-orbital coupling/exchange striction and unveil the relevant dynamics. These proposed studies will have a significant impact not only on specific issues in the field of multiferroics but also on a broad class of multifunctional complex materials, where lattice plays an essential role on the electronic and magnetic properties. The centerpiece of this proposal is a wide spectrum of collaboration, so a multiplicity of techniques and skills will be used. The proposed study will further strengthen the role of research in all levels of education. For example, high school students will be involved in the proposed research through the Partners in Science program, organized by the Liberty Science Center, Jersey City, New Jersey, which the PI has continuously involved in for the last 10 years.