Materials and Mechanisms of Multiferroicity

**非技术摘要**磁性和铁电性是当前技术必不可少的基础，对多铁性材料的探索具有重要的技术和基础意义。磁性和铁电性之间显著的交叉耦合效应往往发生在低温下--远低于室温。为了发现在室温下具有增强的交叉耦合效应的新的多铁性，从而开发具有多铁性的可调谐多功能器件，该项目将研究多铁性的微观起源，试图揭示与耦合效应相关的动力学，并探索新材料。所提出的研究不仅将对多铁性领域的具体问题产生重大影响，而且将对一类广泛的多功能复合材料产生重大影响，在这些材料中，晶格结构对电子和磁性起着至关重要的作用。该提案的核心是广泛的合作，因此将利用多种技术和技能。拟议的研究将进一步加强研究在各级教育中的作用。例如，高中生将通过新泽西州泽西市自由科学中心组织的科学伙伴计划参与拟议的研究，该计划由PI在过去10年中一直参与。**技术摘要**这些项目专注于探索新材料和理解多铁性的机理，其中磁性和铁电性共存，并且可以相互交叉耦合。在这些化合物中，自旋-晶格耦合通常相对较弱，而自旋-晶格耦合是多铁性中新效应的最终驱动力。此外，发生各种自由度耦合的临界温度T_c常常远低于室温。为了发现具有增强的交叉耦合效应和T_c的新的多铁性，从而开发具有多铁性的可调谐多功能器件，本项目将尝试将多铁性与微观的自旋-轨道耦合/交换限制联系起来，并揭示相关的动力学。这些研究不仅将对多铁性领域的具体问题产生重大影响，而且还将对一类广泛的多功能复合材料产生重大影响，因为晶格对其电子和磁性起着至关重要的作用。这项提议的核心是广泛的合作，因此将使用多种技术和技能。拟议的研究将进一步加强研究在各级教育中的作用。例如，高中生将通过科学伙伴计划参与拟议的研究，该计划由新泽西州泽西市自由科学中心组织，过去10年来，PI一直在参与该计划。

**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.