NSF-Europe: Collaborative Study of Geometrically Frustrated Magnetic Material: New Materials and New Physics

NSF-欧洲：几何受挫磁性材料的合作研究：新材料和新物理学

• 批准号: 0353610
• 负责人: Peter Schiffer
• 金额: $ 45.81万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-06-01 至 2008-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0353610&HistoricalAwards=false
• 关键词: NSF; Europe; Collaborative; Study; Geometrically

This is an international collaborative research project that was submitted in response to NSF Solicitation NSF 02-135. The project will investigate the unusual properties of geometrically frustrated magnets, materials in which the interactions between atomic spins compete with each other due to the triangular geometry of the magnetic sublattice. This leads to highly degenerate ground states where the interaction energies cannot all be simultaneously minimized. This in turn prevents ordinary magnetic ordering down to temperatures well below the energy scale of the spin-spin interaction. The low temperature magnetic properties will be investigated via a collaborative approach involving two U.S. investigators, who specialize in materials chemistry and magnetothermodynamic measurements, and two European groups: One in the areas of nuclear magnetic resonance (NMR) and other measurements at Laboratoire de Physique des Solides, Universite Paris-Sud, the other in the areas of neutron diffraction and theory at University College London. One research theme is the chemical synthysis of new geometrically frustrated magnets with the specific goals of investigating new frustrating lattice types and of finding materials that are both highly frustrated and that can be grown as high-quality single crystal samples. The second theme is the study of effects of chemical substitution on geometrically frustrated systems. Students involved in the research will participate in international research activities, together with traditional and cutting edge training that will prepare them for careers in academe, industry or government.%%%This is an international collaborative research project that was submitted in response to NSF Solicitation NSF 02-135. The project will investigate the unusual properties of a class of materials known as geometrically frustrated magnets. In contrast to ordinary magnets, and due to the geometrical arrangement of magnetic atoms in the lattice, these materials cannot attain a unique, low temperature, lowest-energy arrangement for their magnetic moments. The key geometry leading to the effect has magnetic atoms placed at the vertices of triangles. These systems are fundamentally different from other magnetic materials in that their properties at low temperatures cannot be understood within current theoretical models. Understanding geometrical frustration in magnets has implications for complex systems as diverse as superconducting junction arrays or neural networks, and may also provide insight into computational algorithms. The research is a collaboration between four groups, two in the U. S., one in the United Kingdom and one in France. The two U.S. investigators have a long record of working with a diverse group of students and involving graduate students and undergraduates in every stage of the research process. Students involved in the research will participate in international research activities, together with traditional and cutting edge training that will prepare them for careers in academe, industry or government.

这是一个国际合作研究项目，提交给NSF征求NSF 02-135。该项目将研究几何受抑磁体的不寻常特性，这些材料中原子自旋之间的相互作用由于磁子晶格的三角形几何形状而相互竞争。这导致高度简并的基态，其中相互作用能不能全部同时最小化。这反过来又阻止了普通的磁有序度下降到远低于自旋-自旋相互作用的能量标度的温度。低温磁特性将通过合作方法进行研究，涉及两名美国研究人员，他们专门从事材料化学和磁热力学测量，以及两个欧洲小组：一个在南巴黎大学固体物理学实验室的核磁共振（NMR）和其他测量领域，另一个在伦敦大学学院的中子衍射和理论领域。一个研究主题是新的几何受挫磁体的化学合成，其具体目标是研究新的受挫晶格类型，并找到既高度受挫又可以作为高质量单晶样品生长的材料。 第二个主题是研究化学取代对几何挫折系统的影响。参与研究的学生将参加国际研究活动，以及传统和尖端的培训，为他们在商业，工业或政府部门的职业生涯做好准备。这是一个国际合作研究项目，提交给NSF征求NSF 02-135。该项目将研究一类被称为几何受挫磁体的材料的不寻常特性。与普通磁体相反，由于晶格中磁性原子的几何排列，这些材料无法获得其磁矩的独特，低温，最低能量排列。导致这种效果的关键几何结构是将磁性原子放置在三角形的顶点上。这些系统从根本上不同于其他磁性材料，因为它们在低温下的特性无法在当前的理论模型中理解。理解磁体中的几何挫折对超导结阵列或神经网络等复杂系统具有影响，并且还可以提供对计算算法的见解。这项研究是四个小组的合作，其中两个在美国。美国，一个在英国，一个在法国。这两位美国研究人员有着与不同学生群体合作的长期记录，并在研究过程的每个阶段都涉及研究生和本科生。参与研究的学生将参加国际研究活动，以及传统和尖端的培训，为他们在商业，工业或政府的职业生涯做好准备。