Low-Energy Spectroscopy of Correlated Systems

小行星9705442 这是一个新的研究系统的项目，在该系统中，电子相互作用的影响将物理学扩展到简单的固体非相互作用理论的领域之外。 对于此类系统，红外线中通常存在一个特征能量尺度，该尺度将强相关的低能区域与相互作用效应不太重要的高能区域区分开来。 该研究旨在利用 光谱测量，以探测在这一关键的红外范围内的动态，从而发展相关系统的理解。 待研究的具体系统包括近藤绝缘体、混合价系统、由磁序驱动的金属-绝缘体转变和超导体-绝缘体转变系统。这些实验将阐明 这些系统中的电荷动力学，并探讨电荷动力学，磁性，无序和本地化之间的重要关系。结果将提供一个测试和激励的理论工作在这一领域的凝聚态物理学的前沿。 这是一个研究系统的新项目，其中电子相互作用的影响将物理学扩展到简单的固体非相互作用理论的领域之外。 虽然我们对金属和半导体的基本理解是建立在非相互作用电子的理论上，但未来的电子技术 将 日益 包括 材料 在 电子之间的相互作用起了什么作用。 因此，必须充分 了解这些相关电子系统的电子特性，其中发生的现象不能从系统组件（电子和原子核）的知识中轻易预测，而是以非明显的方式从它们之间的相互作用中产生。 （例子包括磁性和超导性。 这一建议是针对红外光谱区的电子动力学研究，其中包括相关的电子态的形成，因此特别重要的能量范围。 待研究的系统包括可被视为相关半导体的稀土化合物，以及磁性和导电性之间的相互作用导致显著效应的氧化物系统（例如，巨磁阻）。 实验结果有望刺激和测试凝聚态物理学前沿在这一领域的理论努力。 ***

9705442 Schlesinger This is a new project to study systems in which the effects of electron interactions extend the physics beyond the domain of simple non-interacting theories of solids. For such systems there is generally a characteristic energy scale in the infrared which separates a strongly correlated low-energy region from a high-energy region in which interaction effects are much less significant. The proposed research seeks to use spectroscopic measurements to probe the dynamics in this crucial infrared range and thereby to develop an understanding of correlated systems. Specific systems to be studied include Kondo insulators, mixed-valent systems, metal- insulator transitions driven by magnetic order, and superconductor- insulator transition systems. These experiments will elucidate the nature of the charge dynamics in these systems, and explore crucial relationships between charge dynamics, magnetism, disorder and localization. Results will provide both a test of and a stimulus for theoretical work in this area at the forefront of condensed matter physics. %%% This is a new project to study systems in which the effects of electron interactions extend the physics beyond the domain of simple non-interacting theories of solids. Although our basic understanding of metals and semiconductors is built on theories of non-interacting electrons, future electronic technologies will increasingly include materials in which interactions between electrons play a role. It is thus important to fully understand the electronic properties of these correlated electron systems, in which phenomena occur that cannot be readily predicted from a knowledge of the system components (the electrons and nuclei), but rather, arise in a non-obvious way from the interactions between them. (Examples include magnetism and superconductivity.) This proposal is directed toward the study o f electron dynamics in the infrared spectral region, which encompasses the energy range relevant to the formation of most correlated electron states and is thus particularly important. Systems to be studied include rare-earth compounds that can be viewed as correlated semiconductors, and oxide systems where an interplay between magnetism and electrical conductivity leads to striking effects (e.g., giant magnetoresistance). The experimental results can be expected to stimulate and test theoretical efforts in this area at the forefront of condensed matter physics. ***