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

探索低载流子密度金属和半导体中的巡回磁性和近磁性状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、磁性和热力学性质上是显而易见的。这种敏感性来自于与那些在经过充分研究的局部磁性系统中发现的机制无关的机制，在这些局部磁性系统中，载流子散射可以由磁场控制。相反，无序、糟糕的屏蔽和强烈的交换相互作用会导致令人惊讶的巨大和强大的量子干涉效应。这些材料对载流子密度、无序和磁性基态的控制，以及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。该计划包括的其他实验包括探索低维系统中的许多身体效应，如块状一维磁体和均匀的超薄膜。这项研究涉及本科生、研究生和为美国而教计划的参与者，他们充分接触了实验科学，从材料的合成、表征和仔细测量，到数据分析和结果发布。许多先进电子设备设计的新概念不仅依赖于电子载流子电荷，还依赖于载流子固有的角动量或自旋。在实现这些新技术方面取得的大部分进展是在半导体和金属系统中取得的，在这些系统中，局部磁矩，即与组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。在这个研究计划中，我们正在探索磁性系统，其中的磁性和电导是由于完全相同的电子，以寻找新的物理性质。这些巡回磁系统可以提供对磁属性和电属性的更大控制，这可能允许创新的设计技术。这个实验计划的重点是探索材料和机制，通过这些材料和机制，对外部参数的敏感性，从而控制物理性能。这项研究涉及本科生、研究生和为美国而教计划的参与者，他们充分接触了实验科学，从材料的合成、表征和仔细测量，到数据分析和结果发布。

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.