Physics of Non-Fermi Liquid Metals

技术总结该奖项支持强关联电子系统的理论研究和教育，特别关注重费米子金属的量子临界性。弱相互作用电子理论很好地描述了传统固态材料的电子性质。然而，在许多材料中，电子关联是重要的，这导致了诸如高温超导和具有质子尺度有效质量的“重”电子等惊人现象。近年来，人们越来越认识到量子临界性在这些材料中扮演着重要的角色。在本文中，重费米子金属代表了原型系统。PI将研究量子临界性倾向于成核新相的概念。几个具体问题将被探讨：首先，PI计划研究最近提出的全球相图中的各种磁相，并研究近藤破坏量子临界点附近的超导性质，费米面在这些临界点经历了很大的波动。第二，PI打算超越最近主要关注于非相互作用系统的拓扑绝缘体的工作，探索重费米子作为一种可以在拓扑相中表现出相互作用效应的环境的可行性。第三，PI将调查最近在Ir基焦绿石重费米子金属上的实验，以了解观察到的大反常霍尔效应的起源。第四，为了在更广泛的背景下阐明量子临界点附近的新激发，PI将探索几个低维系统来研究受量子临界影响的动力学性质。通过拟议的研究，PI将吸引博士后研究员、研究生和本科生。PI还将酌情与国际团体合作，丰富在美国的学生和初级科学家的研究环境。最后，虽然拟议的研究处于基础水平，但它将有助于理解与未来技术相关的先进材料。非技术总结该奖项支持相关电子系统的理论研究和教育。在稀土“重费米子”系统等材料中，电子相互作用强烈，导致电子性质非常不寻常。这里特别关注的是量子临界性，即物质在绝对零度下经历相变的集体行为。这种相变代表了日常生活中常见相变的量子模拟，例如水冻结成冰或蒸发成蒸汽。将开发理论方法来研究量子临界性如何产生新的电子态，如超导，在超导中，电流在没有任何阻力的情况下流动。还需要研究的是电子的磁性和量子力学状态之间的相互作用，这些状态涉及到一种不寻常的拓扑结构。最后，我们将探索低维量子临界系统中的新的动力学性质。这项拟议的研究不仅将吸引初级科学家，还将吸引研究生和本科生。这项研究将有助于理解现代电子材料，这可能对未来的技术很重要。

TECHNICAL SUMMARYThis award supports theoretical research and education in strongly correlated electron systems, with a particular focus on quantum criticality in heavy-fermion metals. Electronic properties in conventional solid-state materials are well described by a theory of weakly interacting electrons. However, there are many materials in which electron correlations are important, which give rise to such striking phenomena as high temperature superconductivity and "heavy" electrons with a proton-scale effective mass. In recent years, there is a growing realization that quantum criticality plays an important role in these materials. Heavy-fermion metals represent prototype systems in this context.The PI will investigate the notion that quantum criticality tends to nucleate new phases. Several specific issues will be explored:First, the PI plans to investigate the various magnetic phases in a recently proposed global phase diagram, and to study the nature of superconductivity near Kondo-destruction quantum critical points where Fermi surfaces undergo large fluctuations.Second, the PI intends to go beyond recent work in topological insulators primarily focused on non-interacting systems, to explore the viability of heavy fermions as a setting in which interaction effects can be manifest in topological phases.Third, the PI will investigate recent experiments on an iridium-based pyrochlore heavy fermion metal to understand the origin of the observed large anomalous Hall effect. Fourth, in order to elucidate novel excitations near quantum critical points in broader settings, the PI will explore several low-dimensional systems to study the dynamical properties that are influenced by quantum criticality.Through the proposed research, the PI will engage postdoctoral fellows, graduate students and undergraduate students. The PI will also collaborate with international groups as appropriate, which enrich the research environment of students and junior scientists in the US. Finally, while the proposed research is at the fundamental level, it will contribute to the understanding of advanced materials relevant to future technologies. NON-TECHNICAL SUMMARYThis award supports theoretical research and education in correlated electron systems. In materials such as the rare-earth-based "heavy-fermion" systems, electrons strongly interact with each other, leading to electronic properties that are highly unusual. A particular focus here is on quantum criticality, the collective behavior of matter undergoing a phase transition at the absolute zero of temperature. Such phase transitions represent the quantum analogue of the familiar phase transitions in daily life, such as water freezing into ice or evaporating into steam. Theoretical methods will be developed to study how quantum criticality gives rise to novel electronic states such as superconductivity, in which electricity flows without experiencing any resistance. Also to be studied is the interplay between magnetism and quantum-mechanical states of the electrons that involve an unusual topology. Finally, novel dynamical properties in quantum critical systems at low dimensions will be explored. The proposed research will engage not only junior scientists but also graduate and undergraduate students. The research will contribute to the understanding of modern electronic materials that may be important for future technologies.