Low Temperature Transport in Cuprate Superconductors and Microwave-Irradiated Two-Dimensional Electron Systems

铜酸盐超导体和微波辐照二维电子系统中的低温输运

• 批准号: 0605919
• 负责人: Adam Durst
• 金额: $ 24万
• 依托单位: SUNY at Stony Brook
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-08-15 至 2009-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0605919&HistoricalAwards=false
• 关键词: Low; Temperature; Transport; Cuprate; Superconductors

The goal of this theoretical project is to extract the essential physics responsible for several measured transport phenomena by performing low temperature transport calculations relevant to the systems of interest and providing guidance for future experiments. The proposed research will focus on three objectives (outlined below), two of which concern the high-Tc cuprate superconductors and the third which concerns microwave-irradiated two-dimensional electron systems. Methods employed range from purely analytical to numerical and include equilibrium and non-equilibrium diagrammatic Kubo formula calculations, semi-classical approaches, electrodynamical stability analyses, solution of the Bogoliubov-de Gennes equation, and partial wave and Born approaches to scattering problems.The first part of the project is a study of the influence of coexisting charge order on quasiparticle transport in a d-wave (cuprate) superconductor. Charge order, recently shown via scanning tunneling microscopy (STM) experiments to coexist with the d-wave superconductivity, could significantly alter the quasiparticle spectrum, gapping out the nodes if sufficiently strong. The principle investigator (PI) and students will calculate the effect this will have on low temperature thermal conductivity, a probe frequently employed to measure the dynamics of quasiparticles in the cuprates.The second part of the project is a study of the contribution of Berry phase effects to the scattering of quasiparticles from magnetic vortices in the vortex state of a d-wave (cuprate) superconductor. The quasiparticle-vortex scattering problem reduces to that of a massless anisotropic Dirac fermion scattering from a non-central effective potential (due to the superflow circulating around the vortex) subject to the Berry phase of (-1) acquired upon circling the vortex. The contribution of Berry phase effects should make the scattering cross-section sensitive to the physics of the vortex core. The PI and students will explore ways to use this effect to probe vortex core physics via thermal transport measurements.The third part of the project concerns the zero-resistance states observed in high-mobility two-dimensional electron systems driven with microwave radiation in a weak magnetic field. Theory predicts that such states are characterized by an inhomogeneous distribution of current flow. The PI and students will study the kinetics of the non-equilibrium transition into this state, the structure of the resulting current distribution, and the nature of its fluctuations.Intellectual merit: The proposed research involves concepts of basic theoretical interest including coexisting charge and superconducting order, dynamics of massless Dirac quasi-particles, Berry phase contribution to quasiparticle-vortex scattering, and non-equilibrium electron dynamics driven by microwave radiation.Broader impact: All of the proposed calculations were inspired by recent experiments and are intended to explain measured transport phenomena and provide guidance for future experiments. Hence, there is potential for impact much larger than the scope of the calculations themselves. Work on quasiparticle transport in the cuprates is intended to provide clues to the larger issue of solving the cuprate problem itself. Work on the microwave problem touches on issues of non-equilibrium pattern formation which apply to a broad range of physical systems. Graduate, undergraduate, and high school students involved in this project will learn much physics and develop a wide range of broadly applicable skills.Non-Technical Abstract:The theoretical research proposed will study transport, the flow of matter or charge, in high temperature superconductors and related materials in hopes of gaining an understanding of their novel properties. Students ranging from high school to graduate school will be involved.

这个理论项目的目标是通过执行与感兴趣的系统相关的低温传输计算，并为未来的实验提供指导，提取负责几个测量传输现象的基本物理。拟议的研究将集中在三个目标（概述如下），其中两个涉及高Tc铜酸盐超导体和第三个涉及微波辐照的二维电子系统。采用的方法范围从纯分析到数值计算，包括平衡和非平衡图解Kubo公式计算，半经典方法，电动力学稳定性分析，Bogoliubov-德Gennes方程的解决方案，和分波和玻恩方法散射problems. First部分的项目是一个研究的影响共存的电荷秩序准粒子输运在d波（铜酸盐）超导体。最近通过扫描隧道显微镜（STM）实验显示，电荷顺序与d波超导共存，可以显着改变准粒子谱，如果足够强，就会使节点断开。主要研究员（PI）和学生将计算这将对低温热导率的影响，这是一种经常用于测量铜氧化物中准粒子动力学的探针。该项目的第二部分是研究Berry相位效应对d波（铜氧化物）超导体涡旋态中磁涡旋准粒子散射的贡献。准粒子涡旋散射问题归结为无质量各向异性狄拉克费米子从非中心有效势（由于涡旋周围的超流循环）散射的问题，该散射受涡旋旋转时获得的Berry相位（-1）的影响。贝里相位效应的贡献应使散射截面对涡核的物理性质敏感。PI和学生将探索如何利用这种效应通过热输运测量来探测涡旋核心物理。该项目的第三部分涉及在弱磁场中用微波辐射驱动的高迁移率二维电子系统中观察到的零电阻状态。理论预测，这种状态的特征是电流的不均匀分布。PI和学生将研究非平衡态过渡到这种状态的动力学，由此产生的电流分布的结构及其波动的性质。智力优势：拟议的研究涉及基本理论感兴趣的概念，包括共存电荷和超导序，无质量狄拉克准粒子的动力学，准粒子涡旋散射的Berry相位贡献，更广泛的影响：所有提出的计算都受到最近实验的启发，旨在解释测量的输运现象，并为未来的实验提供指导。因此，可能产生的影响远远大于计算本身的范围。铜酸盐中准粒子输运的研究旨在为解决铜酸盐问题本身这一更大的问题提供线索。微波问题的工作涉及到非平衡模式形成的问题，适用于广泛的物理系统。研究生、本科生和高中生将在本项目中学习到大量的物理知识，并培养出广泛适用的技能。非技术性摘要：本项目的理论研究将研究高温超导体及其相关材料中的输运、物质或电荷的流动，以期了解它们的新特性。 从高中到研究生院的学生都将参与其中。