Physics of Non-Fermi Liquid Metals

该奖项支持强关联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，具有稀电子的Si-MOSFET，量子点和碳纳米管-其中电子-电子相互作用起着主导作用。 相关电子团体已经接受了这样一种观点，即相互作用会导致费米液体理论的崩溃。 人们仍然知之甚少的是如何做到的！ 这门学科仍处于发展的早期阶段，因此通过范式系统来获得直觉是很重要的，范式系统可以接受受控的理论方法。 还特别有利的是解决系统实验是可能的问题。 考虑到这些因素，将开展以下三个项目：量子临界重费米子：量子临界性与各种强关联系统有着广泛的相关性。 我们将专注于重费米子金属，其中磁量子临界点已被明确确定，并出现了丰富的现象。 我们最近分析了它们的临界动力学，通过一个理论图（局部量子临界性），其中近藤效应的破坏发生在磁性的开始。 本文拟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光谱，霍尔效应与费米表面的演化和波动，由于正交效应可能的赝能隙行为，临界场理论，以及涉及螺旋磁序的量子相变。二维电子气中的相互作用和无序：在Si-MOSFET和相关结构中，电子最紧迫的问题是，在无序的二维电子气中考虑相互作用时，是否会出现金属态。 我们的目标是通过发展一种电子输运的形式主义来阐明这个问题，这种形式主义包含了与无序电子的库仑赝能隙相关的奇异性的影响。磁性量子点作为量子临界玻色-费米近藤模型的实现：我们将研究一个适合于耦合到铁磁金属引线的量子点的模型系统的电子输运。 该系统可以作为玻色-费米近藤模型的一种实现，以及在其量子临界点附近的非费米液体行为。 这些项目将有助于凝聚态社区理解电子材料的广泛影响。 理论和理论方法具有根本意义，材料具有技术意义。 这项工作将涉及研究生和博士后研究员，为培养下一代科学家提供机会。 一些研究将被纳入PI的教学在课堂上设置。 最后，PI将邀请莱斯大学的本科生和莱斯量子研究所赞助的REU学生参与他的研究。该基金支持强关联电子系统的理论研究。 表现出这种行为的材料，其中材料中的电子强烈相互作用，具有许多新颖且无法解释的特性。 对这些材料的研究是现代凝聚态物理学的核心。 然而，同样的材料在技术应用上有很大的希望。这项工作将涉及研究生和博士后研究员，为培养下一代科学家提供机会。 一些研究将被纳入PI的教学在课堂上设置。 最后，PI将邀请莱斯大学的本科生和莱斯量子研究所赞助的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.***