Physics of Non-Fermi Liquid Metals

该奖项支持强相关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。传统固态材料的电子特性可以用弱相互作用电子理论很好地描述。然而，在许多材料中，电子相关性是重要的，它会产生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起着重要的作用。重费米子金属代表了这种情况下的原型系统。PI将研究量子临界倾向于形成新相的概念。将探讨几个具体问题：首先，PI计划研究最近提出的全局相图中的各种磁相，并研究费米表面经历大波动的近道破坏量子临界点附近的超导性质。其次，PI打算超越最近在拓扑绝缘体方面的工作，主要集中在非相互作用系统上，探索重费米子作为相互作用效应可以在拓扑相中表现出来的环境的可行性。第三，PI将调查最近对一种基于铱的焦绿石重费米子金属的实验，以了解观察到的大型异常霍尔效应的起源。第四，为了在更广泛的环境中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特性。通过拟议的研究，PI将聘请博士后，研究生和本科生。PI还将酌情与国际团体合作，这将丰富美国学生和初级科学家的研究环境。最后，虽然拟议的研究是在基础层面，它将有助于理解与未来技术相关的先进材料。该奖项支持相关电子系统的理论研究和教育。在诸如基于稀土的“重费米子”系统等材料中，电子之间的相互作用非常强烈，从而产生了极不寻常的电子特性。这里特别关注的是量子临界性，即在绝对零度温度下经历相变的物质的集体行为。这种相变代表了日常生活中熟悉的相变的量子模拟，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状态，例如超导性，其中电流没有任何阻力。还需要研究的是涉及不寻常拓扑结构的电子的磁性和量子力学状态之间的相互作用。最后，将探讨低维量子临界系统的新动力学性质。这项拟议的研究不仅会吸引初级科学家，还会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.