The Role of Coulomb Interactions in Low Carrier Density, Disordered Sytems

库仑相互作用在低载流子密度、无序系统中的作用

• 批准号: 0103892
• 负责人: John DiTusa
• 金额: $ 28.5万
• 依托单位: Louisiana State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-08-01 至 2005-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0103892&HistoricalAwards=false
• 关键词: Role; Coulomb; Interactions; Low; Carrier

Experiments exploring itinerant magnetic and nearly magnetic states in low carrier density metals and semiconductors are the focus of this research program. Such materials are particularly sensitive to external magnetic fields as is apparent in their transport, magnetic, and thermodynamic properties. This sensitivity results from mechanisms unrelated to those found in the well studied local magnetic systems where carrier scattering can be controlled by magnetic fields. Instead, disorder, poor screening, and strong exchange interactions lead to surprisingly large and robust quantum interference effects. The control over carrier densities, disorder, and magnetic ground states that these materials offer, along with their sensitivity to magnetic fields, suggest that innovative device technologies may result from these investigations. Other experiments included in this program involve the exploration of many body effects in low dimensional systems such as bulk one-dimensional magnets and homogeneous ultra-thin films. This research involves undergraduate as well as graduate students and participants in the Teach For America program who obtain a full exposure to experimental science from the synthesis, characterization, and careful measurement of the materials, to the data analysis and publication of results. %%%Many of the new concepts for advanced electronic device design rely not only on the electronic carrier charge, but also on the carriers intrinsic angular momentum, or spin, as well. Much of the progress in realizing these novel technologies has been made in semiconducting and metallic systems where local magnetic moments, magnetic moments associated with the ions that make up the crystal lattice, are either intrinsic to the material or can be added as impurities. In this research program we are exploring magnetic systems where the magnetism and electrical conduction are due to the very same electrons in order to search for novel physical properties. These itinerant magnetic systems may offer greater control over both the magnetic and electronic attributes, which may allow innovative design technologies. The focus of this experimental program is the exploration of materials and mechanisms by which sensitivity to external parameters, and thus controls of physical properties occur. This research involves undergraduate as well as graduate students and participants in the Teach For America program who obtain a full exposure to experimental science from the synthesis, characterization, and careful measurement of the materials, to the data analysis and publication of results.

探索低载流子密度金属和半导体中巡回磁和近磁态的实验是本研究计划的重点。这种材料对外部磁场特别敏感，这在它们的传输、磁性和热力学性质中是显而易见的。这种敏感性的结果，从机制无关，发现在当地的磁系统，载流子散射可以控制的磁场研究。相反，无序、不良的筛选和强交换相互作用导致了令人惊讶的大而强的量子干涉效应。这些材料对载流子密度、无序和磁基态的控制，沿着它们对磁场的敏感性，表明这些研究可能会产生创新的器件技术。其他实验包括在这个计划涉及许多低维系统，如散装一维磁体和均匀的超薄膜体效应的探索。这项研究涉及本科生以及研究生和美国教学计划的参与者，他们从材料的合成，表征和仔细测量到数据分析和结果的出版，全面接触实验科学。%先进电子器件设计的许多新概念不仅依赖于电子载流子电荷，还依赖于载流子固有角动量或自旋。实现这些新技术的大部分进展都是在半导体和金属系统中取得的，其中局部磁矩，与构成晶格的离子相关的磁矩，要么是材料固有的，要么可以作为杂质添加。在这个研究项目中，我们正在探索磁性和导电归因于相同电子的磁性系统，以寻找新的物理性质。这些巡回磁性系统可以提供对磁性和电子属性的更大控制，这可以允许创新的设计技术。该实验项目的重点是探索材料和机制，通过这些材料和机制对外部参数敏感，从而控制物理特性。这项研究涉及本科生以及研究生和美国教学计划的参与者，他们从材料的合成，表征和仔细测量到数据分析和结果的出版，全面接触实验科学。