Theory of Multiferroic Manganites

9973076 hill该奖项支持对同时表现出磁性、电性和弹性有序的多铁性材料的理论研究。该项目将结合第一性原理局部密度功能和多体电子结构方法来研究钙钛矿结构锰矿的性质，作为这类材料的原型。该项目的总体目标是建立一个多铁性理论，并阐明多铁性和化学相关非多铁性材料之间的区别。将考虑的具体问题包括铋锰矿不寻常的铁磁和铁电行为的起源，反铁磁六方锰矿中铁电的起源，锰矿中磁性和铁电序参数之间的耦合，锰d电子在多铁性行为中的作用，以及电子结构对多铁性锰矿线性和非线性光学性质的影响。对多铁性基础物理的详细了解将有助于寻找新的多铁性材料和设计使用它们的新设备。钙钛矿结构氧化物表现出广泛的磁性和电学性质，如铁电性、铁磁性和压电性。该奖项将支持多铁性材料的理论建模，这些材料同时显示铁电和铁磁，或铁电和反铁磁有序。这些材料在多态存储元件、电场控制铁磁共振器件和磁调制压电换能器等方面具有潜在的技术应用前景。大多数多铁性材料具有非常复杂的晶体结构，因此对多铁性及其磁极化、电极化和结构序参量的相互关系都有很好的了解。该项目将重点关注具有多铁性的钙钛矿结构锰矿，并使用第一性原理技术研究这些材料。该奖项支持的理论工作也将与正在进行的和新的多铁材料研究实验工作相协调。

9973076HillThis award supports theoretical research on multiferroic materials, which exhibit simultaneous magnetic, electric, and elastic ordering. This project will use a combination of first-principles local-density functional and many-body electronic structure methods to investigate the properties of perovskite-structure manganites as prototypes for this class of materials. The overall goals of the project are to construct a theory of multiferroism, and elucidate the differences between multiferroics and chemically related non-multiferroic materials. Specific problems of interest that will be considered include the origin of the unusual ferromagnetic and ferroelectric behavior of bismuth manganite, the origin of ferroelectricity in antiferromagnetic hexagonal manganites, the coupling between magnetic and ferroelectric order parameters in the manganites, the role of the manganese d electrons in multiferroic behavior, and the effects of the electronic structure on linear and nonlinear optical properties of the multiferroic manganites. The detailed understanding of the fundamental physics underlying multiferroism will assist in the search for new multiferroic materials and in the design of new devices which use them.Perovskite structure oxides exhibit a broad range of magnetic and electrical properties such as ferroelectric, ferromagnetic, and piezoelectric behavior. This award will support theoretical modeling of a class of such materials denoted as multiferroic, which show simultaneous ferroelectric and ferromagnetic, or ferroelectric and antiferromagnetic ordering. These materials have potential technological application as multiple-state memory elements, electric-field controlled ferromagnetic resonance devices, and transducers with magnetically modulated piezoelectricity. Most multiferroic materials have very complex crystal structures, and as a result both multiferroism and the interrelation of the magnetic, electric polarization, and structural order parameters are note well understood. This project will focus on perovskite-structure manganites exhibiting multiferroism, and investigate these materials using first-principles techniques. The theoretical work supported under this award will also be coordinated with ongoing and new experimental efforts studying multiferroic materials.