Quantum Spin-Orbital Systems: Models and Spectroscopies

量子自旋轨道系统：模型和光谱

• 批准号: 1005932
• 负责人: Natalia Perkins
• 金额: $ 24.9万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-15 至 2014-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1005932&HistoricalAwards=false
• 关键词: Quantum; Spin; Orbital; Systems; Models

TECHNICAL SUMMARY This award supports theoretical and computational research and educational activities aimed at advancing our understanding of quantum systems, in which spin and orbital degrees of freedom are strongly coupled. Relevant materials are transition metal oxides on frustrated lattices. The research has two parts. The first part is devoted to the study of the fundamental properties of strongly interacting electron systems with coupled spin and orbital fluctuations. Vanadates are perhaps the most prominent examples of spin-orbital systems. The research in this part is motivated by recent experiments on several vanadates including spinel ZnV2O4 and quasi one-dimensional CaV2O4, in which reduced dimensionality appears because of a particular structure of orbital interactions. The PI will study relevant one-dimensional spin-orbital systems. The vanadium chains in these compounds are characterized by frustrated magnetic interactions, Ising-like orbital exchanges, and a large relativistic spin-orbit interaction. Corresponding one-dimensional spin-orbital systems are in many aspects different from the famous one-dimensional SU(4) model. The PI intends to investigate these models using both analytical and numerical theoretical techniques, including bosonization and density matrix renormalization group. The second part of the proposal is devoted to the development of the theory of two-magnon and two-orbiton Raman scattering in coupled spin-orbital systems. This is a challenging but rewarding project as the theory can be readily applied to understanding a variety of existing experimental data in correlated materials with coupled spin and orbital degrees of freedom. Special emphasis will be given to the study of Raman scattering from antiferromagnets, orbitally ordered states, and spin-orbital liquids on frustrated lattices. The PI will be engaged in educational activities at the graduate level aimed at refining and enhancing courses in solid state, statistical and many-body physics. She will develop an advanced course in strongly correlated phenomena in complex systems with special emphasis on new trends in magnetism and transport phenomena. A graduate student will be involved in the research activity. The PI will organize, in collaboration with other faculty from UW-Madison, a Wisconsin Winter School on Modern Condensed Matter and Quantum Information, which will introduce young researchers to various problems in the field and will also improve collaboration between faculty, students, and postdocs from all campuses of the University of Wisconsin system. NONTECHNICAL SUMMARY This award supports theoretical and computational research and educational activities aimed at advancing our understanding of materials, in which the electron spin, an intrinsic quantum mechanical property of electrons, and the motion of the electron strongly interact with each other. The relevant materials are oxides that include transition metals, for example vanadium or zinc, with certain spatial arrangements of atoms leading to spin or spatial distribution of electrons which can occur in many nearly equivalent and hence, competing ways. Achieving a theoretical understanding of the properties of these strongly correlated materials is challenging. Interest in these systems stems in part from the richness of their novel properties: the unexpected variety of ordered states, like various forms of magnetism, the transformations among them, and their sensitivity to stresses, such as applied electric or magnetic fields. The PI will use state-of-the-art analytical as well as computational tools to investigate the physical properties of such transition metal oxides, predict new effects in these materials, and contribute to understanding of experiments. The PI will be engaged in educational activities at the graduate level aimed at refining and enhancing courses in solid state, statistical and many-body physics. She will develop an advanced course in strongly correlated phenomena in complex systems with special emphasis on new trends in magnetism and electron transport phenomena. A graduate student will be involved in the research activity. The PI will organize, in collaboration with other faculty from UW-Madison, a Wisconsin Winter School on Modern Condensed Matter and Quantum Information, which will introduce young researchers to various problems in the field and will also improve collaboration between faculty, students, and postdocs from all campuses of the University of Wisconsin system.

技术摘要该奖项支持理论和计算研究和教育活动，旨在促进我们对量子系统的理解，在该系统中，旋转和轨道自由度强烈地结合在一起。相关材料是沮丧的格子上的过渡金属氧化物。该研究有两个部分。第一部分致力于研究与自旋和轨道波动耦合的强烈相互作用的电子系统的基本特性。杂质也许是旋转轨道系统最突出的例子。该部分的研究是由最近对几种杂质（包括尖晶石Znv2O4和准级CAV2O4）进行的几种杂质实验的动机，其中由于轨道相互作用的特定结构而出现了降低性的降低性。 PI将研究相关的一维自旋轨道系统。这些化合物中的钒链的特征是沮丧的磁相互作用，类似Ising的轨道交换以及较大的相对论自旋轨道相互作用。相应的一维自旋轨道系统在许多方面与著名的一维SU（4）模型不同。 PI打算使用分析和数值理论技术（包括玻体化和密度基质重归其化组）研究这些模型。该提案的第二部分致力于在耦合的旋转轨道系统中的两麦克农和两摩孔拉曼散射的理论的发展。这是一个具有挑战性但有意义的项目，因为该理论可以很容易地应用于与耦合旋转和轨道自由度相关材料中的各种现有实验数据。将特别强调从抗铁磁铁，轨道有序状态以及沮丧的晶格上的旋转轨道液体的拉曼散射研究。 PI将在研究生层面从事教育活动，旨在完善和增强固态，统计和多体物理学的课程。在复杂系统中，她将在复杂的系统中发展一个高级课程，并特别强调磁性和运输现象的新趋势。研究生将参与研究活动。 PI将与威斯康星州冬季有关现代凝聚态和量子信息的威斯康星州冬季学校的其他教师合作组织，这将向年轻的研究人员介绍该领域的各种问题，并将改善威斯康星大学系统所有校园的教职员工，学生和多个校园之间的合作。非技术摘要该奖项支持理论和计算研究和教育活动，旨在促进我们对材料的理解，其中电子旋转，电子的内在量子机械性能以及电子的运动相互互动。相关材料是包括过渡金属（例如钒或锌），具有某些原子的空间排列，导致电子的自旋或空间分布，这些空间排列可以以许多几乎等效的方式发生，因此可以竞争。对这些密切相关的材料的性质有理论上的理解是具有挑战性的。对这些系统的兴趣部分源于它们的新颖性能的丰富性：出乎意料的有序状态，例如各种形式的磁性，它们之间的转换以及它们对应力的敏感性，例如施加的电场或磁场。 PI将使用最先进的分析和计算工具来研究这种过渡金属氧化物的物理特性，预测这些材料中的新效果，并有助于理解实验。 PI将在研究生层面从事教育活动，旨在完善和增强固态，统计和多体物理学的课程。在复杂系统中，她将开发一个高级课程，并特别强调磁性和电子传输现象的新趋势。研究生将参与研究活动。 PI将与威斯康星州冬季有关现代凝聚态和量子信息的威斯康星州冬季学校的其他教师合作组织，这将向年轻的研究人员介绍该领域的各种问题，并将改善威斯康星大学系统所有校园的教职员工，学生和多个校园之间的合作。