Physics of Non-Fermi Liquid Metals

非费米液态金属物理学

• 批准号: 1611392
• 负责人: Qimiao Si
• 金额: $ 33万
• 依托单位: William Marsh Rice University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2019-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1611392&HistoricalAwards=false
• 关键词: Physics; Non; Fermi; Liquid; Metals

NONTECHNICAL SUMMARYThis award supports theoretical research and education in the many-body physics of strongly correlated electrons. For common solids such as silicon or aluminum, their electronic properties are well described by a theory that is based on an assumption of essentially independent electrons. In the recent past, an increasing number of materials have been found to contain electrons that in fact interact strongly with each other. These interactions between electrons give rise to a variety of possible ways in which the electrons can be organized in the material, and create the possibility of phase transitions. These phase transitions are the quantum analogues of familiar phase transitions such as ice melting into water. The PI will develop theoretical methods to i) study the collective behavior of electrons in such settings, ii) understand how novel electronic states can arise, such as superconductivity, in which electrons conduct electricity without experiencing any resistive loss of energy, and iii) explore what happens when the electrons are put under the influence of an external driving force, such as electromagnetic radiation. The research will provide opportunities to train graduate and undergraduate students in cutting-edge theoretical methods, including opportunities for training in an international setting through the PI's collaborations with experimentalists worldwide. The project will contribute to the understanding of modern materials that may be important for future energy and information technologies.TECHNICAL SUMMARYThis award supports theoretical research and education in the many-body physics of strongly correlated electrons. The textbook description of electrons in solids is based on a theory in which electrons only interact weakly with each other. When electron correlations are strong, new theoretical frameworks are needed. A very general effect of electron correlations is to induce transitions between distinct phases of matter at zero temperature. When such quantum phase transitions are continuous, quantum criticality develops and influences physical properties over a wide range of parameters and temperatures. Heavy-fermion systems represent a prototype case where the physics of quantum criticality can be systematically studied. The proposed research concerns the nature of quantum criticality that develops near antiferromagnetic and other types of ground states, as well as new instabilities that develop in the quantum critical regime. Four specific research directions will be pursued:i) The PI will analyze the instabilities of heavy-fermion metals near an antiferromagnetic order. A particular focus of the proposed work is to study the unconventional superconductivity that may develop when the quantum criticality is "beyond-Landau", as characterized by the notion of Kondo destruction.ii) Quantum criticality that involves quadrupolar degrees of freedom will be studied, with a goal of understanding some fascinating experiments that are emerging in several heavy-fermion systems.iii) The PI will explore quantum criticality at the border of a Kondo insulator, in order to shed light on the interplay between Kondo-singlet formation and antiferromagnetic order in a new setting.iv) The PI will address quantum criticality under an external drive. The proposed research aims to gain new insights into the physics of out-of-equilibrium quantum criticality using simplified models in low dimensions.In order to amplify the impact of the PI's theoretical research and expand the educational opportunities for graduate and undergraduate students involved in the PI's research program, the PI intends to continue existing and successful collaborations, and initiate new ones with experimental groups worldwide in this area. The proposed research, while fundamental in nature, will contribute to the understanding of modern materials that may be important for future technologies in energy and information.

非技术性总结该奖项支持强关联电子的多体物理学的理论研究和教育。对于常见的固体，如硅或铝，它们的电子性质可以通过基于基本独立电子假设的理论很好地描述。在最近的过去，越来越多的材料被发现含有电子，实际上彼此强烈相互作用。电子之间的这些相互作用产生了电子在材料中组织的各种可能方式，并产生了相变的可能性。这些相变是熟悉的相变的量子模拟，例如冰融化成水。PI将开发理论方法，i）研究电子在这种环境中的集体行为，ii）了解新的电子状态如何产生，例如超导性，其中电子在没有经历任何电阻性能量损失的情况下导电，iii）探索当电子受到外部驱动力（如电磁辐射）的影响时会发生什么。这项研究将提供机会，培养研究生和本科生在尖端的理论方法，包括培训的机会，在国际环境中通过PI的合作与世界各地的实验家。该项目将有助于理解可能对未来能源和信息技术很重要的现代材料。技术总结该奖项支持强关联电子多体物理学的理论研究和教育。教科书中对固体中电子的描述是基于一种理论，即电子之间只有微弱的相互作用。当电子关联很强时，就需要新的理论框架。电子关联的一个非常普遍的效应是在零温度下诱导物质的不同相之间的跃迁。当这种量子相变是连续的时，量子临界性发展并在宽范围的参数和温度下影响物理性质。重费米子系统代表了一个可以系统地研究量子临界物理的原型案例。拟议的研究涉及在反铁磁和其他类型的基态附近发展的量子临界性的性质，以及在量子临界状态中发展的新的不稳定性。四个具体的研究方向将被追求：i）PI将分析反铁磁序附近的重费米子金属的不稳定性。拟议工作的一个特别重点是研究当量子临界性“超越朗道”时可能发展的非常规超导性，其特征在于近藤破坏的概念。ii）涉及四极自由度的量子临界性将被研究，目的是了解在几个重费米子系统中出现的一些有趣的实验。iii）PI将探索近藤绝缘体边界的量子临界性，以便在新的环境中揭示近藤单线态形成和反铁磁有序之间的相互作用。该研究计划旨在利用低维简化模型对非平衡量子临界物理学进行新的见解。为了扩大PI理论研究的影响力，并扩大参与PI研究计划的研究生和本科生的教育机会，PI打算继续现有的成功合作，并与世界各地的实验小组一起在这一领域发起新的倡议。拟议的研究虽然具有基础性，但将有助于理解可能对未来能源和信息技术至关重要的现代材料。