Physics of Non-Fermi Liquid Metals

该奖项支持强相关电子系统中非费米液体物理的理论研究。到目前为止，有大量的材料——包括高温超导体、重费米子、带有稀电子的硅- mosfet、量子点和碳纳米管——在电子-电子相互作用中起着主导作用。相关电子界已经接受了相互作用可能导致费米液体理论崩溃的观点。人们仍然不太清楚的是，这是如何发生的！这一学科仍处于发展的早期阶段，因此通过范式系统获得直觉是很重要的，这些范式系统适用于受控的理论方法。它也特别有利于解决那些有可能进行系统实验的问题。考虑到这些因素，将进行以下三个项目。量子临界重费米子：量子临界性与各种强相关系统具有广泛的相关性。我们将重点关注重费米子金属，其中磁量子临界点已经明确确定，并且一套丰富的现象学正在出现。我们最近分析了它们的临界动力学，通过一个理论图像（局部量子临界），其中近藤效应的破坏发生在磁性的开始。在此，我们提出对非费米液体的电子性质进行系统的研究。要解决的问题包括单电子谱，霍尔效应与费米表面的演化和波动，由于正交效应可能产生的伪间隙行为，临界场论，以及涉及螺旋磁序的量子相变。二维电子气体中的相互作用和无序：Si-MOSFET及其相关结构中的电子最紧迫的问题是，当在无序的二维电子气体中考虑相互作用时，是否会发生金属态。我们的目标是通过开发电子输运的一种形式来阐明这个问题，它包含了与无序电子的库仑伪间隙相关的奇点的影响。磁性量子点作为量子临界玻色-费米近道模型的实现：我们将研究一个适合于量子点与铁磁性金属引线耦合的模型系统的电子输运。该系统可以作为玻色-费米近道模型的实现，以及非费米液体在其量子临界点附近的行为。这些项目将有助于凝聚态学界对电子材料的广泛理解。理论和理论方法是基础兴趣，材料是技术兴趣。这项工作将涉及研究生和博士后，为培养下一代科学家提供机会。其中一些研究将被纳入PI的课堂教学中。最后，PI将邀请莱斯大学的本科生和莱斯量子研究所资助的REU学生参与他的研究。此基金支持强相关电子系统的理论研究。表现出这种行为的材料，其中材料中的电子相互作用强烈，具有许多新的和无法解释的特性。对这些材料的研究是现代凝聚态物理学的核心。然而，这些相同的材料在技术应用方面具有很大的前景。这项工作将涉及研究生和博士后，为培养下一代科学家提供机会。其中一些研究将被纳入PI的课堂教学中。最后，PI将聘请莱斯大学的本科生和莱斯量子研究所资助的REU学生参与他的研究

This award supports theoretical research on non-Fermi liquid physics in strongly correlated electron systems. There are by now a large number of materials - including high temperature superconductors, heavy fermions, Si-MOSFET's with dilute electrons, quantum dots, and carbon nanotubes - in which electron-electron interactions play a dominant role. The correlated electron community has come to terms with the notion that interactions can lead to a breakdown of Fermi liquid theory. What remains poorly understood is how! The subject is still in its early stage of development, so it is important to try to gain intuitions through paradigmatic systems which are amenable to controlled theoretical approaches. It is also particularly advantageous to address problems for which systematic experiments are possible. With these considerations in mind, the following three projects will be undertaken.Quantum critical heavy fermions: Quantum criticality has broad relevance to a variety of strongly correlated systems. We will focus on heavy fermion metals, in which magnetic quantum critical points have been explicitly identified and a rich set of phenomenology is emerging. We have recently analyzed their critical dynamics, through a theoretical picture (local quantum criticality) in which a destruction of the Kondo effect occurs at the onset of magnetism. Here, we propose to carry out systematic studies on the non-Fermi liquid electronic properties. The issues to be addressed include the single-electron spectrum, Hall effect vs. Fermi surface evolution and fluctuations, possible pseudo-gap behavior due to orthogonality effects, the critical field theory, and quantum phase transitions involving a spiral magnetic order.Interaction and disorder in the two-dimensional electron gas: The most pressing question on the electrons in Si-MOSFET's and related structures is whether a metallic state can occur when interactions are taken into account in a disordered two-dimensional electron gas. We will aim to shed some light on this issue by developing a formalism for the electronic transport, which incorporates the effect of singularities associated with the Coulomb pseudo-gap of the disordered electrons.Magnetic quantum dots as a realization of the quantum critical Bose-Fermi Kondo model: We will study the electronic transport of a model system appropriate for a quantum dot coupled to ferromagnetic metal leads. This system can serve as a realization of the Bose-Fermi Kondo model, and the non-Fermi liquid behavior near its quantum critical point. These projects will contribute to the broad effects to understand electronic materials by the condensed matter community. The theory and theoretical methods are of fundamental interest, and the materials are of technological interest. The work will involve graduate students and postdoctoral fellows, providing opportunities to train the next generation of scientists. Some of the research will be incorporated into the PI's teaching in a classroom setting. Finally, the PI will engage undergraduates from Rice University and REU students sponsored by the Rice Quantum Institute in his research.%%%This grant supports theoretical research on strongly correlated electron systems. Materials exhibiting this behavior, where the electrons in the materials interact strongly, have many novel and unexplained properties. Research into these materials is at the very heart of modern condensed matter physics. Yet, these same materials hold great promise in technological applications.The work will involve graduate students and postdoctoral fellows, providing opportunities to train the next generation of scientists. Some of the research will be incorporated into the PI's teaching in a classroom setting. Finally, the PI will engage undergraduates from Rice University and REU students sponsored by the Rice Quantum Institute in his research.***