Nonequilibrium phenomena in strongly correlated systems

强相关系统中的非平衡现象

• 批准号: 1401908
• 负责人: Alex Levchenko
• 金额: $ 21.6万
• 依托单位: Michigan State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-01 至 2015-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1401908&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.

该奖项支持对脱离稳定平衡状态的新型物质电子态特性的理论研究和教育。纳米尺度材料和材料系统的制造、材料科学和实验技术的最新进展，使得以前所未有的精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。当电子受到严格的空间限制时，它们的波状性质会导致由量子力学控制的干涉效应，粒子之间的相互作用会导致电子形成新的强相关状态。这些系统提供了新的概念科学挑战，可能对未来广泛的电子技术应用有用。在与实验小组的密切合作下，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。与本研究相关的系统包括Luttinger液体，它与量子线相关，量子线具有纳米级直径和微米级长度，可以为电子提供几乎完美的一维环境。被称为量子阱的半导体结构中的电子可以被操纵形成二维液体，如果相互作用足够强，电子可能会结晶。其他相关系统包括最近发现的拓扑绝缘体，它们是绝缘体，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。在某一临界温度以下，它们对导电的电阻率会逐渐消失。PI的目标是研究铁基化合物，其中超导性可能与磁性共存，彼此之间存在微妙的相互作用。这个项目的主要重点是揭示这些系统是如何导电和导热的，它们在外部刺激下的性能有多强，并研究它们潜在实际应用的基本限制。这项研究将对科学界、高等院校理科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达到。重点放在涉及校际科学奥林匹克的外展活动上，并吸引社会经济上处于不利地位和代表性不足的群体的学生考虑从事科学事业。该奖项支持关于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。本项目的主要目的是发展中观和纳米尺度强相关系统的随机动力学和流体动力学理论。技术分析方法以Keldysh场理论为基础，建立在非线性sigma模型和玻色子化技术的框架内。这些理论方法将应用于不同的系统。本项目的目标包括：(1)非平衡非线性，螺旋和螺旋Luttinger液体。该项目旨在研究一般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输运，以及研究具有自旋轨道相互作用的超导体和导线之间的邻近效应现象。(2)强相关二维体系动力学。本研究方向涵盖了流体力学库仑阻力、磁阻自旋介导机制以及二维电子系统在量子化磁场中的光阻新机制等新方面。(3)非常规和拓扑非平衡超导。PI计划研究铁镍超导体的涨落和量子临界性，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发生的输运现象。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问题相关。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。教育方面将通过发展与提议的研究直接有关的课程和通过与研究有关的研讨会、指导和监督校际科学奥林匹克竞赛以及以高中教师为对象的会议加以综合。