X-Ray and Neutron Scattering Studies of Multiferroics with Ferroelectricity Induced by Spin or Charge Order

非技术性：材料的磁性和电学性质具有重要的技术重要性，也具有基本的科学意义。在某些材料中，磁化和电极化之间存在耦合（磁体产生磁场，而电极化材料或铁电体产生电场）。这些材料被称为多铁性材料。多铁性材料在电子和信息存储技术等领域有着广泛的应用前景。最近，发现了两类新的多铁性材料。在一类中，铁电性直接由磁性产生，而在另一类中，由于强量子效应，电性质与磁性耦合。在这两种情况下，磁电耦合都非常强（一个有用的特性），但耦合的物理性质是未知的。该项目致力于使用X射线和中子研究这些材料中磁电耦合的微观起源。这些结果将揭示新的多铁性，并将有助于寻找具有技术上有用的特性的新材料。此外，还将为位于橡树岭、布鲁克海文和其他国家实验室的新国家研究设施培训急需的专家。技术：磁电（ME）多铁性材料是磁性和电极化相互耦合的材料。多铁性材料不仅具有科学价值，而且在信息存储和自旋电子学等领域也具有潜在的应用价值。具有大ME耦合的材料是罕见的。最近，发现了两类新的具有异常大的ME耦合的多铁性：磁驱动的多铁性和铁电体，其中极化是由于强电子相关性（例如电荷顺序）。这些材料中的ME特性的物理学知之甚少。该项目致力于研究几种新型多铁性化合物的晶格和磁性结构：REMn2O5系统，具有电荷顺序的钙钛矿锰氧化物和ReM2O4层状磁体。铁电畸变，磁结构，激发，以及磁场和电场对这些属性的影响将使用X射线和中子散射进行研究。这些研究将有助于阐明ME效应的机制，并有助于设计具有增强性能的新磁电材料。在本项目下培训的学生和博士后将成为散射技术的专家，满足在橡树岭，布鲁克海文和其他国家实验室新建的国家设施人员的迫切需要。该项目还将在最近成立的罗格斯紧急材料中心的主持下促进区域大学之间的合作。

Non-technical:Magnetic and electrical properties of materials are of great technological importance, as well as of fundamental scientific interest. In some materials, there is a coupling between magnetization and electrical polarization (magnets produce magnetic field, while electrically-polarized materials, or ferroelectrics, produce an electric field). These materials are called multiferroics. Multiferroics hold potential for various applications, such as electronics and information storage technologies. Recently, two new classes of multiferroics were discovered. In one class, ferroelectricity results directly from magnetism, and in the other the electrical properties are coupled to magnetism due to strong quantum effects. In the both cases, the magneto-electric coupling is unusually strong (a useful property), but the physics of the coupling is unknown. This project is devoted to investigation of the microscopic origins of the magneto-electric coupling in these materials using x-rays and neutrons. The results will shed light on the new multiferroics, and will help search for new materials with technologically useful properties. In addition, highly-needed specialists for new National research facilities at Oak Ridge, Brookhaven, and other National Laboratories will be trained.Technical:Magnetoelectric (ME) multiferroics are materials in which magnetic and electrical polarizations are coupled to each other. Multiferroics are of scientific interest, and they also hold potential for applications, such as information storage and spintronics. Materials with large ME coupling are rare. Recently, two new classes of multiferroics with unusually large ME coupling were discovered: magnetically-driven multiferroics, and ferroelectrics in which polarization is due to strong electronic correlations (e.g. charge order). The physics of the ME properties in these materials is understood poorly. This project is devoted to investigation of the lattice and magnetic structures of several prominent compound series of new multiferroics: the REMn2O5 system, perovskite manganites with charge order, and ReM2O4 layered magnets. Ferroelectric distortions, magnetic structures, excitations, and effects of magnetic and electric fields on these properties will be investigated using x-ray and neutron scattering. These studies will shed light on the mechanism of the ME effect, and will aid in design of new magnetoelectrics with enhanced properties. Students and postdocs trained under this Project will become specialists in scattering techniques, fulfilling an urgent current need for personnel at newly constructed National facilities at Oak Ridge, Brookhaven, and other National Laboratories. This project will also foster collaboration between regional Universities under the auspices of the recently established Rutgers Center for Emergent Materials.