Spin and Pseudospin Degeneracies in Interacting Electron Systems

9701958戈德堡这个实验研究项目的重点是量子霍尔效应中位于准二维电子气周长附近的“边缘态”形成的导电系统。从根本上说，对于将多个边缘状态引入通信的样本几何形状，预测了新的传输行为。本项目将采用两个几何样例。它们是具有在2D表面鞘上传输的边态的GaAs/AlGaAs超晶格柱；以及具有跨过又长又窄的“线栅”势垒的边缘态传输的门控GaAs/AlGaAs异质结。现有的理论预测将通过使用高场(19特斯拉)、低温(20mK)装置在分子束外延生长的GaAs/AlGaAs异质结样品上进行测量来验证。这一结果有望促进人们对准一维和各向异性三维材料中电子输运的全面理解。%这个研究项目考察了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，在许多重要的技术领域，如大容量存储设备和计算机存储器，磁性起着基础性的作用。我们的计划是开发和检验磁学模型系统的一项试验性努力。只有使用非常纯的模型系统，才能隔离和研究电子相互作用效应。我们的初步结果表明，当你让所有的电子都有磁性排列时，强迫一个电子反转方向会导致它的所有邻居和他们的邻居部分翻转，产生一种漩涡或漩涡。这些被称为Skyrmions的电子漩涡决定了材料的磁性。为了研究Skyrmions，我们团队与朗讯技术公司、奥地利开普勒大学、俄罗斯高压物理研究所和佛罗里达州国家强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，他们将使用新颖的光传输技术一起工作，以“看到”这些电子漩涡，并研究它们最基本的性质。新的显微镜正在开发中，它最终将应用于生物学和DNA测序，超出了该计划的材料科学范围。将使用结合硅技术和光学性能的新材料系统，这将再次在未来几代光电子学中得到应用。***

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. ***