Electron-Electron Interaction Driven Phase Transition in Low Dimensional Systems

* 技术摘要 * 多体电子系统的研究包括两个最基本的课题：电子-电子相互作用和电子-无序相互作用。众所周知，足够的无序会导致电子态经历安德森跃迁。另一方面，强烈的电子-电子相互作用是否也会带来根本性的变化，比如预测的维格纳结晶（电子固体），目前还不得而知。很长一段时间以来，实验工作受到阻碍，因为大多数器件包含高水平的不必要的无序，这使得在低电子密度下的相互作用效应无效。最近在GaAs半导体场效应晶体管中提供超高质量二维电子系统方面取得了突破性进展。该项目将利用这种具有创纪录的低电子密度的设备在低温下进行输运实验。目标是验证强电子-电子相互作用是否驱动一级相变（维格纳结晶）或一些中间相。这两种观测都将为理解固体或强相关液体形式的强相互作用电子的量子力学性质提供见解。该项目将支持一名博士的教育。学生追求发现和学习最先进的技术，这在历史上已被证明是科学职业的优秀培训。电子是存在于所有物理系统中的量子力学对象，大多数系统都包含大量电子。了解电子的状态，它们如何与环境相互作用，是一个重要的科学课题，并在推进现代科学和技术方面发挥了关键作用。与水类似，电子在高温下表现为气态，在低温下表现为液态。另一种形式的状态是固体，它被预测但从未被观察到。获得这种电子固态的证据不仅对理解电子之间最基本的力如何从根本上影响量子态很重要，而且还允许科学家在开发量子电子学和自旋电子学中利用显着的特性。随着纳米技术标志着21世纪世纪的开始，半导体技术有了很大的改进。由于最近的一项突破，一种新型的超高纯度半导体已经成为可能。该项目将利用这些设备进行最先进的科学工具实验：纳米纤维和超低温物理学。我们的目标是捕捉直接的证据，要么表明一个电子固体，或其他一些复杂的状态。该项目将支持一名博士的教育。该组织还鼓励学生参与探索和学习最先进的技术，并允许该组织与当地高中开展外联活动。

****Technical Abstract****The study of the many-body electron systems encompasses two of the most fundamental subjects: electron-electron interaction and electron-disorder interaction. It is well known that sufficient disorder causes electron states to undergo Anderson Transition. On the other hand, whether strong electron-electron interaction also brings radical changes, such as the predicted Wigner Crystallization (electron solid), is still unknown. For a long time, experimental effort was hindered because most devices contain a high level of unwanted disorder which overwhelms the interaction effect at low electron densities. Recent breakthroughs have been made in providing ultra-high quality two-dimensional electron systems in GaAs semiconductor field-effect-transistors. This project will utilize this type of devices with record low electron densities to perform transport experiments at low temperatures. The goal is to verify whether strong electron-electron interaction drives a first-order phase transition (Wigner crystallization) or some intermediate phases. Either observation will provide insights in understanding the quantum mechanical nature of strongly interacting electrons in the form of a solid or a strongly correlated liquid. This project will support the education of one Ph.D. student in pursuing discovery and in learning most advanced technologies, which has historically shown to be excellent training for scientific careers.****Non-Technical Abstract****Electrons are quantum mechanical objects that exist in all physical systems and most systems contain a large number of them. Understanding the states of electrons, how they interact with the environment and each other, is a vital scientific subject and has played a critical role in advancing modern science and technologies. Analogous to water, electrons manifest both gaseous states at high temperatures and liquid states at low temperatures. Another form of the states is solid which was predicted but never observed. To obtain evidence of this solid state of electrons is not only important to understand how the most basic force among the electrons can radically affect the quantum states, but also allow scientists to utilize remarkable properties in developing quantum electronics and spintronics. As nanotechnology marks the opening of the 21st century, semiconductor technologies have greatly improved. A novel type of semiconductors of ultra-high purity has become available as a result of a recent breakthrough. This project will utilize such devices to perform experiments with the most advanced scientific tools: nanofabrication and ultra-low temperature physics. The goal is to capture direct evidences that either indicate an electron solid, or some other complex states. This project will support the education of one Ph.D. student in pursuing discovery and in learning most advanced technologies, and allow the group to conduct outreach activities with local high schools.