Electron Transport in Correlated Low-Dimensional Systems

相关低维系统中的电子传输

• 批准号: 9812422
• 负责人: Philip Phillips
• 金额: $ 19.8万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-08-01 至 2001-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9812422&HistoricalAwards=false
• 关键词: Electron; Transport; Correlated; Low; Dimensional

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. ***

9812422菲利普斯这是一项由材料研究和化学系联合资助的理论基金。研究集中在三个主题上：稀薄二维电子气中的反常相变；电子中的输运；以及近藤效应中的无序。当电子被限制在平面内运动时，局域化以及电子关联都会增强。这项资助侧重于空间受限电子系统的三种不同的物理实现，在这些系统中，输运性质从根本上与局域化、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，重点是Kravchenko和他的同事最近的实验，这些实验提供了令人信服的证据，证明在稀薄的2D电子气中存在导电态。这些实验令人惊讶，因为之前人们认为无序排除了2D中金属导电的存在。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Wigner晶体熔化时，熔化的液态超导。讨论了一系列的解析和数值方法来验证这一建议。在第二个问题中，我们重点研究了导电体K+(密码2.2.2)e-中磁性和无序之间的相互作用。电子是一类有机导体，其中的阴离子是电子。导致这一系统输运和磁性复杂的关键特征是存在局域的自旋单电子对，没有伴随的自旋能隙，但却有令人惊讶的电荷能隙。我们认为，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，佐丹诺和他的同事的实验表明，在金属薄膜中，弱局域化物理可以耦合到近藤自旋反转散射。作为前人关于非磁散射对近藤效应的反馈效应的工作的扩展，我们将进行磁阻的标度分析和计算。这是一项由材料研究部和化学系联合资助的理论基金。研究集中在三个主题上：稀薄二维电子气中的反常相变；电子中的输运；以及近藤效应中的无序。所有这三个问题都有一个共同点，那就是电子相互作用之间的竞争，以及电子对一维和二维系统的限制。***