Theory of Highly Correlated Electronic Systems

高度相关电子系统理论

• 批准号: 0531196
• 负责人: Steven Kivelson
• 金额: --
• 依托单位: Stanford University
• 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: 2004-09-01 至 2008-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0531196&HistoricalAwards=false
• 关键词: Theory; Highly; Correlated; Electronic; Systems

This award supports theoretical research in fundamental condensed matter physics. The Fermi-liquid description of weakly interacting quasiparticles has been remarkably successful as a framework for treating the properties of the electron fluids encountered in a wide variety of crystalline materials and solid state devices, even where the electron-electron interactions are quite strong, and the Fermi liquid parameters are strongly renormalized from their bare values. However, there are also many cases where the Fermi liquid approach qualitatively fails: systems in which whatever dispersing feature there are in the single particle spectral functions are overdamped in the sense that their widths are larger than their mean, or where there are phase transitions to broken symmetry states with temperature and energy scales comparable to microscopic electronic scales, or that exhibit macroscopic behaviors that are inconsistent with weakly interacting quasiparticles, such as finite resistance in a two-dimensional system in the low temperature limit, or metallic(increasing with increasing temperature) resistivities with magnitudes in excess of the Ioffe-Regel limit. Non-interacting electrons serve as the appropriate paradigmatic for well developed Fermi liquids, but simple, solvable models of strongly interacting electrons are few and far between. It is the principle purpose of the research envisaged here to obtain well controlled approximate, or even asymptotically exact solutions to simple models of strongly interacting electrons as a step in filling this void. More particularly, it is proposed to study models with purely repulsive interactions between electrons in which the existence of a superconducting state with a high transition temperature can be firmly established and the transition temperature reliably estimated. This study is relevant to elucidating the mechanism of high temperature superconductivity. On a more phenomenological level, it is proposed to study the effects of electronic micro-phase-separation, a common occurrence in strongly correlated "bad metals," on various macroscopic properties such as the optical conductivity and DC transport. While much of this effort is inspired by an attempt to understand the remarkable properties of the cuprate high temperature superconductors, applications of related ideas to low density electron gases in MOSFET's, and to other highly correlated electronic materials, such as transition metal oxides and the organic superconductors, are also planned.There are, by now, many examples of highly correlated bad metals, where conventional approaches to the theory of electronic structure fail. Obtaining a simple, qualitative understanding of these materials is an intellectual question on par with, "What is a metal?" High temperature superconductivity is only one of the phenomena observed in such materials, but one of the most exciting.This work will serve as a fertile source of research projects for students. The problems are well defined, and of direct experimental relevance, while at the same time involving mastery of a large number of methods of many body physics. %%%This award supports theoretical research on fundamental condensed matter physics. The topic is materials which exhibit strongly interacting electrons which produce effects, such as high temperature superconductivity, that are unable to be understood with current theory. A systematic procedure will be followed to develop and solve models, including experimental predictions, which will contribute to the understanding of these materials. As part of this project, students will be trained in modern techniques of condensed matter theory.***

该奖项支持基本凝结物理学的理论研究。 弱相互作用的准粒子的费米 - 液体描述非常成功，作为处理在各种晶体材料和固态设备中遇到的电子流体的特性的框架，即使电子电子相互作用也很强，并且FERMI液体参数从其裸露的值中得到了强烈的恢复。 However, there are also many cases where the Fermi liquid approach qualitatively fails: systems in which whatever dispersing feature there are in the single particle spectral functions are overdamped in the sense that their widths are larger than their mean, or where there are phase transitions to broken symmetry states with temperature and energy scales comparable to microscopic electronic scales, or that exhibit macroscopic behaviors that are inconsistent with weakly interacting quasiparticles,例如在二维系统中的有限耐药性，在低温极限下，或金属（随温度增加）电阻率，大小超过IOFFE-REGEL极限。 非相互作用的电子作为发达的费米液体的适当范式，但是强烈相互作用的电子的简单，可解决的模型很少，而且相距甚远。 这是这里设想的研究的主要目的，以获取对强烈相互作用电子模型的简单模型，以获取良好控制的近似解决方案，以作为填充该空隙的一步。 更特别地，建议研究电子之间纯粹的排斥相互作用的模型，在这些模型中，可以牢固地建立具有高过渡温度的超导状态，并且过渡温度可靠地估计。 这项研究与阐明高温超导性的机理有关。 在更现象的学水平上，有人提出研究电子微相分离的影响，这是在强烈相关的“不良金属”中的常见发生，这是对各种宏观特性（例如光导电性和直流运输）的效果。 尽管大部分努力的启发是通过试图了解高温高温超导体的显着特性，相关思想在MOSFET中的低密度电子气体以及其他高度相关的电子材料（例如过渡金属氧化物和有机体超导体）中的应用程序的应用程序。 对这些材料的简单，定性的理解是一个智力问题：“什么是金属？” 高温超导性只是这种材料中观察到的现象之一，但最令人兴奋的是这项工作将是学生研究项目的肥沃来源。 这些问题的定义很好，并且是直接的实验性相关性，同时涉及许多身体物理学的大量方法的掌握。 %%％该奖项支持有关基本冷凝物质物理学的理论研究。 该主题是表现出强烈相互作用的电子的材料，这些电子产生效果，例如高温超导性，而当前理论无法理解。 将遵循一个系统的程序来开发和解决模型，包括实验预测，这将有助于理解这些材料。 作为该项目的一部分，学生将接受凝结物质理论的现代技术培训。***