U.S.-Federal Republic of Germany Cooperative Research: Microscopic and Phenomenological Theories of Correlated Fermi Systems

美德合作研究：相关费米系统的微观和唯象理论

• 批准号: 8922642
• 负责人: Peter Hirschfeld
• 金额: $ 1.45万
• 依托单位: University of Florida
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1990
• 资助国家: 美国
• 起止时间: 1990-09-01 至 1994-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8922642&HistoricalAwards=false
• 关键词: U.S.; Federal; Republic; Germany; Cooperative

This award supports Professors P. J. Hirschfeld and K. A. Muttalib of the University of Florida to maintain collaborative research links with Dr. Peter Woelfle of the Institute for Condensed Matter Theory of the University of Karlsruhe, Federal Republic of Germany. They plan to investigate superconductivity and magnetism using the single band Hubbard model, which is possibly relevant to materials with high superconducting transition temperatures ("high-Tc materials.") They will apply two new methods that they recently developed: 1) a new functional integral approach, and 2) a conserving slave boson diagrammatic expansion, to study several questions related to the possibility of superconductivity in Hubbard-like systems, the stability of the Fermi liquid state in the presence of strong correlations, and the stability of incommensurate antiferro- magnetic phases. They will also study models of unconventional superconductivity, with an emphasis on the question of how the symmetry of an unconventional order parameter can be determined with external probes, particularly electromagnetic ones. Although the mechanisms responsible for pairing in the high temperature superconductors remain mysterious even after two years of intense research since its discovery, there is accumulating evidence that electronic correlations, rather than electron-phonon interaction play a crucial role. Unfortunately, there is no adequate systematic and controlled method available for dealing with such strongly correlated systems. New methods such as those being used here are essential for the study of all highly correlated Fermi systems, and should be generally applicable to any similar model, including that appropriate for the high-Tc materials. These novel methods originated as a result of extensive collaboration among these scientists when Dr. Woelfle spent several years at the University of Florida. Continuing the interaction should prove to be very productive and mutually beneficial.

该奖项支持佛罗里达大学的P. J. Hirschfeld教授和K. A. Muttalib，以维持与德国联邦共和国Karlsruhe大学凝结物问题理论的Peter Woelfle博士的合作研究联系。 They plan to investigate superconductivity and magnetism using the single band Hubbard model, which is possibly relevant to materials with high superconducting transition temperatures ("high-Tc materials.") They will apply two new methods that they recently developed: 1) a new functional integral approach, and 2) a conserving slave boson diagrammatic expansion, to study several questions related to the possibility of superconductivity in Hubbard-like systems, the在存在较强相关性的情况下，费米液态的稳定性以及抗抗磁相的稳定性。 他们还将研究非常规超导性的模型，并重点是如何使用外部探针，尤其是电磁探针来确定非常规阶参数的对称性的问题。 尽管即使在发现自发现以来进行了两年的激烈研究，但导致高温超导体配对的机制仍然是神秘的，但有累积的证据表明，电子相关性，而不是电子相互作用，而不是电子相互作用起着至关重要的作用。 不幸的是，没有足够的系统和受控的方法可用于处理如此强相关的系统。 诸如此处使用的新方法对于研究所有高度相关的费米系统至关重要，通常应适用于任何类似的模型，包括适合高-TC材料的模型。 这些新颖的方法起源于这些科学家在佛罗里达大学度过了几年的科学家之间的广泛合作。 继续进行互动应该被证明是非常有生产力和互惠互利的。