Disorder and the Emergence of Inhomogeneous Phases in Strongly Correlated Electron Systems

强相关电子系统中的无序和非均匀相的出现

• 批准号: 1407502
• 负责人: Peter Hirschfeld
• 金额: $ 30万
• 依托单位: University of Florida
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-01 至 2017-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1407502&HistoricalAwards=false
• 关键词: Disorder; Emergence; Inhomogeneous; Phases; Strongly

NON-TECHNICAL SUMMARYThis award supports research and education designed to advance our understanding of materials containing mobile electrons that interact strongly with each other, giving rise to new states of matter with novel superconductive properties. Superconductivity is a quantum state of many electrons in a metal that is characterized by the loss of electrical resistance and consequently of all dissipation of energy. The materials to be investigated include cuprate and Fe-based superconductors, as well as iridate systems. The PI's group will use model calculations for electrons to study several problems directed towards a broader understanding of how these materials work. In particular the fundamental physics of defects and impurities that can destroy or nucleate superconducting states under different circumstances will be studied. These investigations will result in a deeper understanding of the nature of high temperature superconductivity. Understanding properties of correlated electron systems and the influence of disorder may lead to novel materials properties that could be utilized in new devices and technologies, obtaining unusual sensitivity operating near transitions between competing phases that occur in highly correlated electron systems. This could have enormous technological implications. The award will support training of graduate students. The PI's group will engage in outreach activities to educate schoolchildren in the Gainesville area about physics, hold public and colloquium talks on superconductivity, and offer information on research activities at a public level through the extensive website. TECHNICAL SUMMARYThis award supports theoretical research and education to address long-standing fundamental problems of quenched disorder and various types of competing emergent order in correlated electron systems. The materials to be investigated include cuprate and Fe-based superconductors, as well as iridate systems. The Fe-based superconductors exhibit a wide variety of behavior suggesting that the electronic responses to external perturbations that break xy symmetry are extremely strong, and may be important for superconductivity. Both electron-doped cuprate superconductors and Fe-based superconductors exhibit phases where itinerant spin density wave order coexists with superconductivity. Properties of electronic states in these materials will be studied through a careful analysis of simplified models of interacting electrons on the lattice, informed in some cases by microscopic density functional theory calculations. The PI's group will also study the influence of impurities on electronic nematic instabilities in Fe-based superconducting systems at temperatures above the superconducting transition. To achieve research goals the full numerical and analytical calculations of the superconducting critical temperature and order parameter in the Hubbard model across its phase diagram, including the spin density wave and coexistence phases within a fluctuation exchange interaction approximation will be performed.

非技术摘要该奖项支持旨在促进我们对含有彼此强烈相互作用的移动电子的材料的理解的研究和教育，从而产生具有新颖超导特性的新物质状态。 超导性是金属中许多电子的量子态，其特征是电阻损失，从而导致所有能量耗散。待研究的材料包括铜酸盐和铁基超导体，以及铱酸盐系统。 PI 的团队将使用电子模型计算来研究几个问题，以更广泛地了解这些材料的工作原理。 特别是，将研究在不同情况下可以破坏或使超导态成核的缺陷和杂质的基础物理。这些研究将使人们更深入地了解高温超导的本质。了解相关电子系统的特性和无序的影响可能会产生可用于新设备和技术的新颖材料特性，从而在高度相关电子系统中发生的竞争相之间的转变附近获得异常的灵敏度。这可能会产生巨大的技术影响。该奖项将支持研究生的培训。 PI 的小组将开展外展活动，对盖恩斯维尔地区的学童进行物理教育，举办有关超导性的公开演讲和学术讨论会，并通过广泛的网站提供公共层面的研究活动信息。 技术摘要该奖项支持理论研究和教育，以解决相关电子系统中猝灭无序和各种类型的竞争性涌现秩序的长期存在的基本问题。待研究的材料包括铜酸盐和铁基超导体，以及铱酸盐系统。 铁基超导体表现出各种各样的行为，表明电子对破坏 xy 对称性的外部扰动的响应非常强，并且可能对超导性很重要。 电子掺杂铜酸盐超导体和铁基超导体都表现出流动自旋密度波序与超导性共存的相。 这些材料中电子态的性质将通过仔细分析晶格上相互作用的电子的简化模型来研究，在某些情况下通过微观密度泛函理论计算来了解。 PI 的小组还将研究在高于超导转变的温度下杂质对铁基超导系统中电子向列不稳定性的影响。 为了实现研究目标，将对哈伯德模型中的超导临界温度和有序参数在其相图中进行全面的数值和分析计算，包括涨落交换相互作用近似中的自旋密度波和共存相。