Theory of Superconductivity in Correlated Electron Systems

相关电子系统中的超导理论

• 批准号: 8813852
• 负责人: ROBERT JOYNT
• 金额: $ 10.13万
• 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: 1988
• 资助国家: 美国
• 起止时间: 1988-09-15 至 1992-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8813852&HistoricalAwards=false
• 关键词: Theory; Superconductivity; Correlated; Electron; Systems

A program of braodly-based theoretical research into superconductivity is proposed, ranging from the microscopic description of the superconductive mechanism in high-Tc superconductors to the investigation of flux-pinning in high- field Niobium-Titanium superconducting magnets. In the microscopic work, the approach is to construct variational wavefunctions for the ground and excited states of the two- dimensional Hubbard model. The investigator has recently found an expression for the excited states, building on earlier work for the ground state. The energy and other properties of these can be evaluated using a numerical technic previously developed by the investigator and others. They also propose to continue to develop the analytic theory of this model to finite temperatures, using a recently discovered mapping of the entropy into a well- understood statistical mechanical problem. Further work aimed at determining the microscopic phase of UPt3 using experimental neutron-scattering data as input will be pursued. Collaboration with experimental groups at Wisconsin will also continue. The model of granular superconductivity to explain properties of weakly-connected superconductors will be explored by numerical methods. Numerical solutions of the Ginsburg-Landau equations for different flux-pinning morphologies (experimentally determined) will be obtained.. These last two projects will help to optimize the properties of oxide and Niobium-Titanium magnets.

从高温超导体超导机制的微观描述到强场Nb-Ti超导磁体的磁通钉扎研究，提出了一套基于布拉德的超导理论研究方案。在微观工作中，方法是构造二维Hubbard模型的基态和激发态的变分波函数。这位研究人员最近在基态的早期工作的基础上，找到了激发态的一个表达式。可以使用研究人员和其他人先前开发的数值技术来评估这些物质的能量和其他性质。他们还建议利用最近发现的将熵映射到一个众所周知的统计力学问题的方法，继续发展这个模型在有限温度下的分析理论。将继续开展以实验中子散射数据为输入来确定UPt3微观相的进一步工作。与威斯康星州的实验小组的合作也将继续。我们将用数值方法探索解释弱连接超导体性质的颗粒超导模型。对于不同的磁通钉扎形态(实验确定的)，将得到Ginsburg-Landau方程的数值解。后两个项目将有助于优化氧化物和Nb-钛磁体的性能。