Spin, Charge, and Disorder in Correlated Metals

相关金属中的自旋、电荷和无序

• 批准号: 9507873
• 负责人: Thomas Rosenbaum
• 金额: $ 25.5万
• 依托单位: University of Chicago
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-08-01 至 1998-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9507873&HistoricalAwards=false
• 关键词: Spin; Charge; Disorder; Correlated; Metals

9507873 Rosenbaum The physics of the metal-insulator transition is intimately tied to the unusual ground state properties of highly-correlated metals, including the heavy fermions compounds, the high-Tc superconductors, and the Mott-Hubbard systems V2O3 and Ni(S,Se)2. An important, unresolved issue is the nature of the interplay of the itinerant magnetism with the Coulomb interactions and the disorder. This research project focuses on the transition metal oxides and sulfides. It aims to deconvolute the influences of the spin and charge degrees of freedom in the barely-delocalized, disordered metal through a program of electrical transport, magnetic susceptibility, specific heat, neutron scattering, and optical measurements. Temperature capabilities down to the milliKelvin regime provide new diagnostics of localization and electron interaction effects as well as simplifying the theoretical description of the problem. Moreover, possible deviations from the usual Fermi-liquid behavior, with different forms posited for the quantum and classical regimes, should be revealed by high-resolution pressure studies of the transport and calorimetric response. %%% A sharp change from a state where electrons can flow freely to one where they are unable to move lies at the heart of many device applications. This "metal-Insulator" transition can be driven by a number of external parameters, including the application of pressure, the introduction of disorder, and the manipulation of material characteristics. The research proposed here seeks to explore the interaction between disorder, found in all real materials, and control parameters such as changing electron density and internal chemical pressure at the boundary between metal and insulator. Of prime interest are transition metal oxides and sulfides, classes of materials whose electronic and magnetic responses are acutely sen sitive to small changes in the control parameters. Depending on the particular material and the nature of its preparation, it may have potential as an electronic switch, a magnetic storage device, or a high- temperature superconductor. ***

9507873 Rosenbaum金属-绝缘体转变的物理学与高度相关金属的不寻常基态性质密切相关，包括重费米子化合物，高Tc超导体和Mott-Hubbard系统V2 O3和Ni（S，Se）2。 一个重要的，尚未解决的问题是性质的相互作用的巡回磁库仑相互作用和无序。 本研究项目的重点是过渡金属氧化物和硫化物。它旨在通过电输运、磁化率、比热、中子散射和光学测量的程序来解卷积几乎离域的无序金属中的自旋和电荷自由度的影响。 温度能力低至 毫开尔文状态提供了定位和电子新诊断 交互作用以及 简化 对问题的理论描述。 此外，委员会认为， 通过对输运和量热响应的高分辨率压力研究，可以揭示出与通常的费米液体行为的可能偏差，以及量子和经典状态的不同形式。 从电子可以自由流动的状态到电子无法移动的状态的急剧变化是许多器件应用的核心。这种“金属-绝缘体”转变可以由许多外部参数驱动，包括 压力的应用，无序的引入，以及材料特性的操纵。这里提出的研究旨在探索在所有真实的材料中发现的无序与控制参数之间的相互作用，例如改变金属和绝缘体之间边界处的电子密度和内部化学压力。最感兴趣的是过渡金属氧化物和硫化物，这类材料的电子和磁性响应对控制参数的微小变化非常敏感。根据特定的材料及其制备的性质，它可能具有作为电子开关、磁存储器件或磁存储器件的潜力。 高温超导体 ***