Electron Transport in Correlated Low-Dimensional Systems

9812422 Phillips这是一项由材料研究和化学部门共同资助的理论基金。主要研究三个方面：稀二维电子气体中的异常相变；电子输运；以及近藤效应中的混乱。当电子被限制在一个平面上运动时，局域化和电子相关性都得到增强。这项资助的重点是空间受限电子系统的三种不同的物理实现，其中输运性质从根本上与定位、电子相互作用或两者之间的相互作用有关。在第一个系统中，重点放在Kravchenko及其同事最近的实验上，这些实验为稀二维电子气体中导电状态的存在提供了令人信服的证据。这些实验是令人惊讶的，因为以前人们认为，无序排除了二维金属传导的存在。在这项工作中，探索了实验观察到的转变对应于维格纳晶体熔化的可能性。我们提出当维格纳晶体熔化时，熔化的液态超导。讨论了一系列的分析和数值方法来验证这一建议。在第二个问题中，我们重点研究了电导体K +(cryptand 2.2.2)e -中的磁性和无序之间的相互作用。电子是一类以阴离子为电子的有机导体。导致该系统的输运和磁性复杂的关键特征是存在自旋单线态电子对，这些电子对定位在没有伴随的自旋间隙的空腔中，而是令人惊讶的电荷间隙。我们认为，一个具有长程磁相互作用的模型可以解释该系统的输运性质。最后，佐丹奴及其同事的实验表明，在金属薄膜中，弱局部化物理可以耦合到近藤自旋翻转散射。一个尺度分析以及磁电阻的计算将被做作为以前的工作的扩展，在非磁散射对近藤效应所起的反馈效应。这是一项由材料研究部和化学部联合资助的理论基金。主要研究三个方面：稀二维电子气体中的异常相变；电子输运；以及近藤效应中的混乱。这三个问题的共同点是电子相互作用和电子限制在一维和二维系统之间的竞争。＊＊＊

9812422 Phillips This is a theoretical grant funded jointly by the Divisions of Materials Research and Chemistry. The research focuses on three topics: the unusual phase transition in the dilute two-dimensional electron gas; transport in electrides; and, disorder in the Kondo effect. When electrons are confined to move in a plane, localization as well as electron correlations are enhanced. This grant focuses on three distinct physical realizations of spatially confined electron systems in which the transport properties are fundamentally linked to localization, electron interaction, or an interplay between the two. In the first system, the focus is on the recent experiments of Kravchenko and colleagues which provide convincing evidence for the existence of a conducting state in a dilute 2D electron gas. These experiments are surprising as it had been previously thought that disorder precludes the presence of metallic conduction in 2D. In this work, the possibility that the experimentally-observed transition corresponds to the melting of a Wigner crystal is explored. We propose that when a Wigner crystal melts, the melted liquid state superconducts. A series of analytical and numerical approaches are discussed to test this proposal. In the second problem, we focus on the interplay between magnetism and disorder in the electride conductor K +(cryptand 2.2.2 )e -. Electrides are a class of organic conductors in which the anion is an electron. The key features that lead to the complexity of the transport and magnetic proerties of this system are the presence of spin singlet electron pairs localized in cavities without the concomitant spin gap, but instead a surprising charge gap. We argue that a model with long range magnetic interactions can explain the transport properties of this system. Finally, experiments by Giordano and co-workers show that in thin metallic films, weak-localization physics can couple to Kondo spin-flip scattering. A scaling an alysis as well as a calculation of the magnetoresistance will be done as extensions of previous work on the feedback effect played by non-magnetic scattering on the Kondo effect. %%% This is a theoretical grant funded jointly by the Divisions of Materials Research and Chemistry. The research focuses on three topics: the unusual phase transition in the dilute two-dimensional electron gas; transport in electrides; and, disorder in the Kondo effect. All three problems have in common the competition between electron interactions and the confinement of electrons to one-and two-dimensional systems. ***