Collaborative Research: Search for the Zero-Magnetic-Field Wigner Solid

合作研究：寻找零磁场维格纳固体

• 批准号: 1309337
• 负责人: Sergey Kravchenko
• 金额: $ 20万
• 依托单位: Northeastern University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-07-01 至 2018-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1309337&HistoricalAwards=false
• 关键词: Collaborative; Research; Search; Zero; Magnetic

****TECHNICAL ABSTRACT****First predicted by Eugene Wigner in 1934, the realization of the electronic solid (Wigner Crystal) which forms when the interactions between electrons strongly exceed their kinetic energy has been a long-standing challenge. A classical Wigner crystal has been realized for electrons on the surface of liquid helium, and possible evidence of crystallization of quantum electron systems has been obtained in strong magnetic field. The aim of this project is to realize the quantum Wigner crystal in zero field, to obtain definitive evidence of its existence, and to study its formation as a function of temperature, magnetic field, electron density and disorder. The search for the zero-field Wigner solid is especially promising at this time because: (a) we have recently obtained compelling evidence that there is a genuine phase transition in a dilute 2D electron system driven by interactions to a low-density phase that may be a precursor phase or the Wigner Crystal itself; (b) samples are now available that far exceed the quality of the samples used 20 years ago in which measurements suggested the possibility of Wigner crystallization. We will investigate the nonlinear transport and noise spectra of low-density, low-disorder, strongly correlated two-dimensional electron systems in metal-oxide semiconductor field-effect transistors (MOSFETs) and strained silicon quantum wells in Si/SiGe heterostructures. This project will support the education of a PhD student in these advanced technologies, which has historically shown itself to be excellent training for many scientific careers from academia to our most advanced technology industries.****NON-TECHNICAL ABSTRACT****In most metals, electrons behave like a gas and move randomly through the structure formed by the massive positive ions. Eugene Wigner predicted in 1934 that when the energy of motion of the electrons is much lower than the energy of interaction between them, the electron gas will instead freeze into a lattice, forming a "Wigner crystal" or "Wigner glass". Realized for electrons on the surface of liquid helium, and possibly in semiconductors in strong magnetic field, the Wigner solid has not been found in semiconductors in the absence of magnetic field. By measurements of the nonlinear resistance and noise spectra of low-density two-dimensional electron systems in silicon metal-oxide semiconductor field-effect transistors (MOSFETs) and Si/Si-Ge heterostructures, we plan to realize and investigate the long sought-after zero field Wigner crystal, thereby providing opportunities for studies in a heretofore unexplored region, and adding a deeper fundamental understanding of semiconductors - materials that are of great importance to our current technology. This project will support the education of a PhD student in these advanced technologies, which has historically shown itself to be excellent training for many scientific careers from academia to our most advanced technology industries.

****技术摘要****由尤金·维格纳于1934年首次预测，当电子之间的相互作用强烈超过其动能时形成的电子固体（维格纳晶体）的实现一直是一个长期的挑战。在液氦表面实现了电子的经典维格纳晶体，并获得了在强磁场下量子电子系统结晶的可能证据。本课题的目标是在零场中实现量子维格纳晶体，获得其存在的确切证据，并研究其形成与温度、磁场、电子密度和无序度的关系。寻找零场维格纳固体目前特别有希望，因为：(a)我们最近获得了令人信服的证据，证明在相互作用驱动的稀二维电子系统中存在真正的相变，该相变可能是前驱相或维格纳晶体本身；(b)现在可获得的样品质量远远超过20年前使用的样品，当时的测量表明可能存在维格纳结晶。我们将研究金属氧化物半导体场效应晶体管（mosfet）和Si/SiGe异质结构中应变硅量子阱中低密度、低无序、强相关二维电子系统的非线性输运和噪声谱。该项目将支持博士研究生在这些先进技术方面的教育，从历史上看，这对从学术界到我们最先进的技术行业的许多科学事业都是极好的培训。****非技术摘要****在大多数金属中，电子的行为像气体一样，在由大量正离子形成的结构中随机移动。1934年尤金·维格纳预言，当电子的运动能量远低于它们之间的相互作用能量时，电子气体反而会冻结成晶格，形成“维格纳晶体”或“维格纳玻璃”。实现了电子在液氦表面，并可能在强磁场的半导体中，在没有磁场的半导体中没有发现维格纳固体。通过测量硅金属氧化物半导体场效应晶体管（mosfet）和Si/Si- ge异质结构中低密度二维电子系统的非线性电阻和噪声谱，我们计划实现和研究长期追求的零场维格纳晶体，从而为迄今尚未探索的领域提供研究机会。并增加了对半导体材料的更深入的基本理解，这对我们当前的技术非常重要。该项目将支持博士研究生在这些先进技术方面的教育，从历史上看，这对从学术界到我们最先进的技术行业的许多科学事业都是极好的培训。

项目成果

Metallic state in a strongly interacting spinless two-valley electron system in two dimensions

• DOI: 10.1103/physrevb.101.045302
• 发表时间: 2020-01-14
• 期刊: PHYSICAL REVIEW B
• 影响因子: 3.7
• 作者: Melnikov, M. Yu;Shashkin, A. A.;Kravchenko, S., V
• 通讯作者: Kravchenko, S., V