Physics of Non-Fermi Liquid Metals

非技术总结该奖项支持强关联电子多体物理的理论研究和教育。对于常见的固体，如硅或铝，它们的电子性质可以用一个建立在基本独立电子假设基础上的理论很好地描述。在最近的过去，越来越多的材料被发现含有事实上相互作用强烈的电子。电子之间的这些相互作用引起了电子在材料中组织的各种可能的方式，并创造了相变的可能性。这些相变是常见相变的量子模拟，比如冰融化成水。PI将开发理论方法来i)研究电子在这种环境中的集体行为，ii)了解新的电子态是如何产生的，例如超导，其中电子导电而不经历任何阻性能量损失，以及iii)探索当电子受到外部驱动力(例如电磁辐射)影响时会发生什么。这项研究将为研究生和本科生提供培训尖端理论方法的机会，包括通过PI与世界各地的实验者合作在国际环境下进行培训的机会。该项目将有助于理解现代材料，这些材料可能对未来的能源和信息技术很重要。技术总结该奖项支持强关联电子的多体物理的理论研究和教育。教科书中对固体中电子的描述是基于一个理论，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不同相之间的跃迁。当这样的量子相变是连续的时，量子临界性会在广泛的参数和温度范围内发展并影响物理性质。重费米子系统代表了一个可以系统研究量子临界物理的原型案例。这项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，以及在量子临界区发展的新的不稳定性。具体的研究方向有四个：i)PI将分析重费米子金属在反铁磁序附近的不稳定性。这项拟议工作的一个特别的重点是研究当量子临界性为“Beyond-Landau”时可能发展的非常规超导电性，其特征是近藤破坏的概念。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，以揭示在新的设置下近藤单态形成和反铁磁秩序之间的相互作用。iv)PI将解决外部驱动下的量子临界性。这项拟议的研究旨在通过使用低维简化模型来获得对非平衡量子临界物理学的新见解。为了扩大PI理论研究的影响，并扩大参与PI研究计划的研究生和本科生的教育机会，PI打算继续现有的和成功的合作，并与世界各地的实验小组在这一领域发起新的合作。拟议的研究虽然具有基础性，但将有助于理解现代材料，这些材料可能对未来的能源和信息技术非常重要。

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.