Spin and Pseudospin Degeneracies in Interacting Electron Systems

相互作用电子系统中的自旋和赝自旋简并性

• 批准号: 9701958
• 负责人: Bennett Goldberg
• 金额: $ 25.45万
• 依托单位: Trustees of Boston University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-09-01 至 2001-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9701958&HistoricalAwards=false
• 关键词: Spin; Pseudospin; Degeneracies; Interacting; Electron

9701958 Goldberg This experimental research project focuses on conducting systems formed by the "edge states" that lie near the perimeter of quasi- two dimensional electron gases in the quantum Hall effect (QHE). Fundamentally new transport behavior is predicted for sample geometries that bring multiple edge states into communication. Two sample geometries will be employed in this project. These are a GaAs/AlGaAs superlattice pillar with edge states communicating on a 2D surface sheath; and a gated GaAs/AlGaAs heterojunction with edge states communicating across a long, narrow "line gate" barrier. Existing theoretical predictions in these cases will be tested with measurements to be made using a high-field (19Tesla), low temperature (20mK) apparatus on samples fabricated from MBE-grown GaAs/AlGaAs heterostructures. It is expected that the results will advance general understanding of electronic transport in quasi-1D- and in anisotropic 3D- materials. %%% This research program examines ways in which electrons interact with each other to create ordered or collective structures. In many materials systems magnetism is driven by electronic interactions and in many technologically important areas like mass storage devices and computer memory, magnetism plays a fundamental role. Our program is an experimental effort to develop and examine model systems of magnetism. Only by using very pure model systems can the electronic interaction effects be isolated and studied. Our preliminary results have shown that when you have all electrons magnetically aligned, then forcing one to flip its orientation cause all its neighbors and their neighbors to turn to partially flip, creating a kind of swirl or vortex. These swirls of electrons, called Skyrmions, determine the magnetic properties of the material. To study Skyrmions, our group has built collaborations with Lucent Technology, the Kepler University in Austria, the Institute of High Pressure Physics in Russia, and the National High Magnetic Field Laboratory in Florida. The group encompasses students from high-school summer interns, to undergraduate and graduate students who will work together using novel techniques of light transmission to "see" these electron swirls and study their most fundamental properties. New microscopes are being developed, which will have eventual application in biology and DNA sequencing, extending beyond the materials science of this program. New materials systems combining silicon technology with optical properties will be used, which again will have application in future generations of optoelectronics. ***

小行星9701958 该实验研究项目的重点是在量子霍尔效应（QHE）中由准二维电子气周边附近的“边缘态”形成的导电系统。 从根本上说，新的运输行为预测样品的几何形状，使多个边缘状态进入通信。 本项目将采用两种样品几何形状。 这些是GaAs/AlGaAs超晶格柱，其边缘状态在2D表面鞘层上通信;以及栅极GaAs/AlGaAs异质结，其边缘状态跨越长而窄的“线栅极”势垒通信。 现有的理论预测，在这些情况下，将测试与测量使用高场（19 Tesla），低温（20 mK）的装置上制作的样品MBE生长的GaAs/AlGaAs异质结构。 预计这些结果将促进对准一维和各向异性三维材料中电子输运的一般理解。 本研究项目研究电子相互作用以创建有序或集体结构的方式。 在许多材料系统中，磁性是由电子相互作用驱动的，在许多技术重要的领域，如大容量存储设备和计算机存储器，磁性起着基础作用。 我们的计划是一个实验性的努力，发展和检查模型系统的磁性。 只有使用非常纯的模型系统才能分离和研究电子相互作用效应。 我们的初步结果表明，当你让所有的电子磁性对齐时，强迫一个电子翻转它的方向会导致它的所有邻居和他们的邻居转向部分翻转，从而产生一种漩涡或漩涡。 这些电子漩涡，称为Skyrmions，决定了材料的磁性。 为了研究Skyrmions，我们的团队与朗讯科技、奥地利开普勒大学、俄罗斯高压物理研究所和佛罗里达的国家高磁场实验室建立了合作关系。 该小组包括从高中暑期实习生到本科生和研究生的学生，他们将一起使用新颖的光传输技术来“看到”这些电子漩涡并研究它们最基本的特性。 新的显微镜正在开发中，最终将应用于生物学和DNA测序，超出了该计划的材料科学。 将使用将硅技术与光学特性相结合的新材料系统，这将再次应用于未来几代光电子学。 ***