Complex Electron Solids Forming in the Two-dimensional Electron Gas

非技术摘要条状和气泡状图案在许多物理、化学和生物系统中自发形成。在这些模式的起源，人们经常会发现经典的力具有相互竞争的长程和短程相互作用。在电子系统中，形成了这些图案的量子力学类似物，但与它们的经典对应物相比，这些量子力学相在很大程度上是未被探索的。PI提出了实验研究和教育活动，以解决在二维电子片中形成的具有条状和泡状形貌的电子固体的性质的突出问题。该团队将通过调整电子相互作用和检查量子力学效应来研究这些电子固体。该项目提供了一个极好的机会，培训研究生和本科生在现代电子物理、半导体纳米制造、低温和灵敏电子测量方面的技能，这些技能是成功的科学和技术载体所必需的。国际学生联合会已经参与并将继续与代表人数不足的群体的学生合作。此外，印第安纳州的初中生和高中生将通过开展演示和探究活动，希望激励他们开始科学和工程事业。技术摘要二维电子气可能最著名的是整数和分数量子霍尔效应。二维电子气的另一个显著特性是，当无序度足够低时，载流子有序形成复杂的电子固体。这种电子固体在高质量的电子气中大量存在，这些电子气被限制在GaAs/AlGaAs量子阱中。电子固体的一个例子是维格纳晶体。然而，当电子聚集时，会形成更复杂的固体。电子泡沫相是由于这些电子团簇在六方晶格上的有序所致，而所谓的量子霍尔向列相是这些团簇的丝状排列。在这些电子固体中，基本量子力学显然发挥了作用，因为它们是稳定的，因为单个电子的波函数重叠。该团队研究了量子力学波函数的结构和电子-电子相互作用的调谐对复杂电子固体的影响。此外，该团队还研究了最近发现的与复合费米子结晶有关的磁传输信号，复合费米子是分数量子霍尔区的浮现粒子。将采用各种运输技术。计划中的实验提供了对在二维电子气中形成的不同类型的电荷有序相的本质的洞察。这些知识有助于加深对量子多体系统和其他凝聚态系统中电子固体的理解，并从长远来看，可能导致在量子计量学中的应用。我们的实验还通过研究电子固体和分数量子霍尔态之间的相变，提供了关于深入研究分数量子霍尔态的见解。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 abstractStripe-like and bubble-like patterns spontaneously form in numerous physical, chemical, and biological systems. At the origin of these patterns one often finds classical forces with competing long-range and short-range interactions. In electron systems quantum mechanical analogues of these patterns form, but in contrast to their classical counterparts, these quantum mechanical phases are largely unexplored. The PI proposes experimental research and educational activities addressing outstanding questions on the nature of electron solids with stripe-like and bubble-like morphologies that form in a two-dimensional electron sheet. The team will study these electron solids by tuning the electron interactions and by examining quantum mechanical effects. This project offers an excellent opportunity to train graduate and undergraduate students in modern electron physics, semiconductor nanofabrication, cryogenics, and sensitive electronic measurements, skills that are necessary for a successful carrier in science and technology. The PI has involved and will continue to work with students from underrepresented groups. Furthermore, middle and high school students throughout the state of Indiana will be reached through the development of demonstrations and inquiry based activities with the hope of inspiring them to embark on a career in the sciences and engineering.Technical abstractThe two-dimensional electron gas is perhaps best known for the integer and fractional quantum Hall effect. Another remarkable property of the two-dimensional electron gas is that, when the disorder level is low enough, charge carriers order into complex electron solids. Such electron solids are abundant in high quality electron gases confined to GaAs/AlGaAs quantum wells. One example for electron solids is the Wigner crystal. However, more complicated solids form when electrons cluster. The electronic bubble phase is due to ordering of these electron clusters on a hexagonal lattice and the so called quantum Hall nematic is a filamentary arrangement of these clusters. In these electron solids elementary quantum mechanics is clearly at play, since they are stabilized as wavefunctions of individual electrons overlap. The team investigates the influence of the structure of the quantum mechanical wavefunction and the effect of the tuning of the electron-electron interaction on the complex electron solids. In addition, the team investigates recently found magnetotransport signatures associated with a crystallization of composite fermions, the emergent particles of the fractional quantum Hall regime. Various transport techniques will be employed. The planned experiments provide insight into the nature of the different types of charge ordered phases forming in the two-dimensional electron gas. Such knowledge contributes to an enhanced understanding of quantum many-body systems and of the electron solids in other condensed matter systems and, in the long term, may lead to possible applications in quantum metrology. Our experiments also offer insight pertaining to the intensely studied fractional quantum Hall states through studies of the phase transitions between the electron solids and the fractional quantum Hall states.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.