Probing Exotic Phases of Ultra High Mobility Two-Dimensional Electrons

非技术描述：固体科学和工程中的一个主要研究领域是研究固体中的电子如何相互作用。这种相互作用源于电子之间的斥力，因为它们的电荷，以及它们的自旋和其他自由度。它导致了奇异的、通常是意想不到的物质相。要研究这些相和现象，重要的是要尽量减少杂质和缺陷等缺陷，使电子-电子相互作用成为主导因素。这个项目的目标是从实验上探索和理解在具有最少缺陷的电子系统中出现的新相。研究成果通过出版物和会议报告向专业以及普通科学和工程界传达。虽然这一项目的主题是根本性的，但从长远来看，这一领域的进展有利于社会，因为它可能导致电子设备和信息处理系统的新的、变革性的概念，例如量子计算机，其运行依赖于量子和/或相互作用现象。该项目还纳入了高质量和全面的教育内容，因为它包括对学生进行关键的、最先进的科学技术领域的教育，包括非常高质量的薄膜半导体结构的制造、表征和物理。这些领域训练有素的学生对美国和世界其他地区都是宝贵的资源。技术描述：这个项目包括对量子受限的GaAs/AlGaAs半导体结构中电子相互作用物理的实验研究，这些结构具有超高质量，通过它们创纪录的高迁移率和新的多体状态来量化。该计划包括通过分子束外延技术进行制造，以及在电子相关现象占主导地位的低温和高磁场下的电子传输特性的研究。这项工作的重点是二维电子和空穴系统，限制在选择性掺杂的GaAs量子阱中。在所有固态材料中，二维电子系统具有最高的迁移率，而二维空穴系统中较大的有效质量和较强的自旋-轨道相互作用为其电子性质增加了额外的、新的扭曲。在这个项目的过程中，我们研究了这些相互作用的二维载流子系统的几个奇特的相，包括分数量子霍尔效应，复合费米子，维格纳晶体，以及条状和泡状相。目前正在研究分数量子液体和维格纳晶体在大垂直磁场(小朗道能级填充因子)以及激发朗道能级多体态之间的竞争。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Non-technical Description:A major research area in solid-state science and engineering is the study of how the electrons in a solid interact. The interaction stems from the repulsion between electrons because of their electric charge, as well as their spin and other degrees of freedom. It leads to exotic, often unexpected, phases of matter. To study these phases and phenomena, it is important to minimize the imperfections, such as impurities and defects, so that electron-electron interaction is the dominating factor. The goal of this project is to experimentally explore and understand the new phases that arise in electron systems with the least amount of imperfections. Results of the research are communicated through publications and conference presentations to the specialized as well as general science and engineering communities. While the subject of this project is fundamental, progress in this area benefits society in the long term as it may lead to novel, transformative concepts for electronic devices and information processing systems, such as a quantum computer, whose operation relies on quantum and/or interaction phenomena. The project also incorporates a high quality and comprehensive educational component as it includes the education of students in critical, state-of-the art areas of science and technology, including the fabrication, characterization, and physics of very high-quality, thin-film semiconductor structures. Well-trained students in these fields are invaluable resources for the US as well as for the rest of the world. Technical Description:This project encompasses experimental investigations of electron interaction physics in quantum-confined GaAs/AlGaAs semiconductor structures with ultra-high-quality, as quantified by their record-high mobilities and new many-body states. The program includes studies of both fabrication via the molecular beam epitaxy technique, and of the electronic transport properties at low temperatures and high magnetic fields where electron correlation phenomena dominate. The emphasis of the work is on two-dimensional electron and hole systems confined to selectively doped GaAs quantum wells. The two-dimensional electron systems have the highest mobility among all solid-state materials, while the larger effective mass and the strong spin-orbit interaction in two-dimensional hole systems add additional, novel twists to their electronic properties. Several exotic phases of these interacting two-dimensional carrier systems are studied during the course of this project; these include the fractional quantum Hall effect, composite fermions, Wigner crystal, and stripe and bubble phases. Competition between the fractional quantum liquid and the Wigner crystal at large perpendicular magnetic fields (small Landau level filling factors), as well as many-body states in excited Landau levels are being investigated.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.