Nonequilibrium phenomena in strongly correlated systems

强相关系统中的非平衡现象

• 批准号: 1606517
• 负责人: Alex Levchenko
• 金额: $ 21.51万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2018-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1606517&HistoricalAwards=false
• 关键词: Nonequilibrium; phenomena; strongly; correlated; systems

NONTECHNICAL SUMMARY This award supports theoretical research and education on the properties of novel electronic states of matter that are driven out of the steady state of equilibrium. Recent advances in fabrication of materials and materials systems at the nanoscale, in materials science, and in experimental techniques have made it possible to investigate novel electronic systems and quantum mechanical phenomena with an unprecedented level of accuracy and control. When electrons are tightly spatially confined, their wave-like nature results in interference effects governed by quantum mechanics, and the interaction between the particles leads to a formation of novel strongly correlated states of electrons. These systems offer new conceptual scientific challenges and may be useful for a wide spectrum of future electronic technological applications. In close collaboration with experimental groups, the PI aims to investigate transport properties, for example how these systems conduct electricity, with an emphasis to discover new transport phenomena.Systems relevant to this investigation include Luttinger liquids, which are relevant to quantum wires which have a nanometer scale diameter and a micrometer scale length leading to an almost perfect one-dimensional environment for electrons. Electrons in semiconductor structures called quantum wells can be manipulated to form two-dimensional liquids, and if interactions are sufficiently strong the electrons may crystallize. The other relevant systems include recently discovered topological insulators, which are insulators in the bulk but almost perfect ideal conductors at the surface or edge of the sample. Superconductors are an important focus of the project. They display vanishing resistivity to conducting electricity below a certain critical temperature. The PI aims to investigate iron-based compounds where superconducting properties may coexist with magnetic properties with a delicate interplay between each other. The main emphasis of this project is on revealing how these systems conduct electricity and heat, how robust are their properties under external stimuli, and studying their fundamental limits of their potential practical applications. The research will have a broad impact on the scientific community, postsecondary science students, and public audiences. These audiences will be reached, respectively, through conferences and journal publications, formal university courses, and an extensive public science engagement program. A strong emphasis is placed on outreach activities involving the interscholastic science olympiad, and attracting students from socioeconomically disadvantaged and underrepresented groups to consider careers in science.TECHNICAL SUMMARY This award supports theoretical research and education on nonequilibrium and transport properties of several confined low-dimensional materials and materials systems where low dimensionality plays a role. The primary aim of this project is to develop a stochastic kinetic and hydrodynamic theory of meso and nanoscale strongly correlated systems. The technical analytical methods are based on Keldysh field theory built into the framework of the nonlinear sigma model and bosonization technique. These theoretical approaches will be applied to various systems. The goals of this project include: (1) Out of equilibrium nonlinear, spiral and helical Luttinger liquids. The PI aims to study quantum quench relaxation and thermalization in generic nonintegrable one-dimensional liquids, reveal emergent physics phenomena beyond the Luttinger liquid paradigm, investigate transport at the edges of quantum spin Hall insulators, and investigate proximity effect phenomena between superconductors and wires with spin-orbit interaction. (2)Kinetics of strongly correlated two-dimensional systems. This research direction covers new aspects of hydrodynamic Coulomb drag, spin-mediated mechanisms of magnetodrag as well as novel mechanisms of photoresistance of two-dimensional electron systems in a quantizing magnetic field. (3)Unconventional and topological nonequilibrium superconductivity. The PI plans to investigate fluctuations and quantum criticality in the iron-pnictide superconductors, search for novel collective modes in the coexistence phase and to describe dynamics initiated by optical excitation. The PI will also develop thermomagnetic transport theory of Pauli limited ultra-thin superconducting films and study transport phenomena occurring at the surface states of topological insulators and superconductors.A postdoctoral researcher and graduate students working on this project will receive extensive training by studying modern aspects of condensed matter physics, developing new conceptual approaches to nonequilibrium systems and conducting original research. The technical and theoretical methods that will be developed as a part of this project are relevant to a much wider class of problems in the quantum physics of many-body systems. The results of the proposed work will be widely disseminated in publications, seminars, colloquia and conference presentations. Educational aspects will be integrated through the development of courses directly related to the proposed research and through research-related seminars, coaching and supervising interscholastic science olympiads, and meetings that target high-school teachers.

非技术性总结该奖项支持理论研究和教育的新的电子状态的物质，被赶出平衡的稳定状态的属性。 最近在纳米级材料和材料系统的制造、材料科学和实验技术方面的进展使得以前所未有的精确度和控制水平研究新型电子系统和量子力学现象成为可能。当电子在空间上受到严格限制时，它们的波动性质导致量子力学控制的干涉效应，粒子之间的相互作用导致形成新的强关联电子态。这些系统提供了新的概念科学的挑战，并可能是有用的未来电子技术应用的广泛范围。通过与实验组的密切合作，PI旨在研究传输特性，例如这些系统如何导电，重点是发现新的传输现象。与此研究相关的系统包括Luttinger液体，这与具有纳米尺度直径和微米尺度长度的量子线有关，导致电子几乎完美的一维环境。在称为量子威尔斯的半导体结构中，电子可以被操纵形成二维液体，如果相互作用足够强，电子可以结晶。其他相关的系统包括最近发现的拓扑绝缘体，它是大块的绝缘体，但在样品的表面或边缘几乎是完美的理想导体。超导体是该项目的一个重要焦点。在低于某一临界温度时，它们的导电电阻率会消失。PI旨在研究铁基化合物，其中超导性能可能与磁性共存，彼此之间存在微妙的相互作用。该项目的主要重点是揭示这些系统如何导电和传热，它们在外部刺激下的性能有多强，以及研究它们潜在实际应用的基本限制。 这项研究将对科学界，中学后科学学生和公众产生广泛的影响。这些受众将分别通过会议和期刊出版物，正式的大学课程和广泛的公共科学参与计划来实现。该奖项的重点是开展校际科学奥林匹克活动，吸引来自社会经济弱势群体和代表性不足群体的学生考虑从事科学职业。技术概要该奖项支持对几种受限低维材料和低维材料系统的非平衡和输运性质的理论研究和教育。该项目的主要目的是发展一个随机动力学和流体动力学理论的中，纳米级强关联系统。技术分析方法是基于Keldysh场理论的非线性西格玛模型和玻色化技术的框架内建立。这些理论方法将适用于各种系统。本项目的目标包括：（1）非平衡非线性、螺旋和螺旋Luttinger液体。PI旨在研究通用不可积一维液体中的量子猝灭弛豫和热化，揭示超越Luttinger液体范式的新兴物理现象，研究量子自旋霍尔绝缘体边缘的传输，并研究超导体和具有自旋轨道相互作用的导线之间的邻近效应现象。（2）强关联二维系统的动力学。该研究方向涵盖流体动力学库仑阻力的新方面、磁阻力的自旋介导机制以及量子化磁场中二维电子系统光阻的新机制。（3）非常规和拓扑非平衡超导。PI计划研究铁-磷属元素化物超导体中的波动和量子临界性，在共存阶段寻找新的集体模式，并描述由光激发引发的动力学。PI还将发展泡利极限超薄超导薄膜的热磁输运理论，并研究拓扑绝缘体和超导体表面态的输运现象。从事该项目的博士后研究员和研究生将通过研究凝聚态物理的现代方面，开发非平衡系统的新概念方法和进行原创性研究来接受广泛的培训。作为该项目的一部分，将开发的技术和理论方法与多体系统量子物理学中更广泛的一类问题有关。拟议工作的结果将在出版物、研讨会、座谈会和会议发言中广泛传播。教育方面将通过与拟议的研究直接相关的课程的开发，并通过与研究有关的研讨会，辅导和监督校际科学奥林匹克，并针对高中教师的会议。