Interplay between symmetry breaking, quasiparticles and their topology in quantum condensed matter systems.

量子凝聚态物质系统中对称破缺、准粒子及其拓扑之间的相互作用。

• 批准号: 1506756
• 负责人: Oskar Vafek
• 金额: $ 29.92万
• 依托单位: Florida State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-15 至 2019-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1506756&HistoricalAwards=false
• 关键词: Interplay; between; symmetry; breaking; quasiparticles

NONTECHNICAL SUMMARYThis award supports theoretical research and education on materials that can be tuned to display seemingly contradictory properties of matter, such as electrical insulation and superconductivity, an electronic state that can conduct electricity without dissipation. The goal of the research is to develop a better mathematical description of the underlying dynamical processes that cause such differentiation in the observed properties of the same physical system. The ultimate motivation is that understanding how the constituents of the system globally organize in different states will allow improved material design and control that take advantage of the proximity and interplay between these states.In a parallel project, the PI plans to study the mechanisms of Hall transport of heat in a class of superconductors with unusual properties compared to the simple, elemental superconductors. Hall transport of heat occurs in a material in the presence of magnetic field, and results in a temperature difference in the sample in a direction perpendicular to the magnetic field. Analysis and interpretation of experimental measurements of this type of heat transport in superconductors can help researchers distinguish between the various possible mechanisms that can cause superconductivity, and clarify the degree of competition between them. In addition, this project will enable training and mentoring of young scientists via participation in cutting-edge research.This award also supports the continuation of a Wiki textbook project which delivers freely available textbooks written by students based on faculty lecture notes. The PI plans to further build on this project expanding to new courses to become a vehicle for the dissemination of scientific knowledge.TECHNICAL SUMMARYThis award supports theoretical research and education aimed to develop a comprehensive theoretical description for a class of poorly understood phenomena in correlated quantum condensed matter systems, in which spontaneous symmetry breaking, quasiparticles, and their topology are inextricably linked. The projects involves analytical and numerical work on theoretical models that display on equal footing propensity towards spontaneous symmetry breaking into correlated non-superconducting states, as well as unconventional superconducting states that emerge in the vicinity of the latter. In addition, it explores Berry phases as a novel mechanism for thermal Hall transport of non-Landau quasiparticles, with the goal of developing a reliable tool for extracting valuable spectroscopic information from experimental data.Among the objectives are: determining the energy distribution of the Berry curvature of the quasiparticle wavefunctions in the mixed state of unconventional superconductors with different pairing symmetries; identifying the physical processes which control the recently discovered thermal activation scale of thermal Hall conductivity in what may otherwise be gapless systems; development of models of the vortex core which capture strong correlations; constructing a theory which would allow the study of the physical states both above and below the transition temperature in model systems with a multitude of interfering ordering tendencies; exploring the effects of charge-carrier doping of the quantum critical point associated with the transition between the Dirac semi-metal and the antiferromagnetic insulator on the honeycomb monolayer; further development of a theory of two- and three-dimensional quadratic band touching in physically motivated systems. The approach to all of these projects involves a combination of analytical and numerical methods of quantum many-body and/or field theory.This award also supports the continuation of a Wiki textbook project which delivers freely available textbooks written by students based on faculty lecture notes. The PI plans to further build on this project expanding to new courses to become a vehicle for the dissemination of scientific knowledge.

该奖项支持对材料的理论研究和教育，这些材料可以被调谐以显示看似矛盾的物质特性，例如电绝缘和超导性，一种可以导电而不耗散的电子状态。这项研究的目标是发展一种更好的数学描述潜在的动力过程，这些过程导致在同一物理系统中观察到的特性中出现这种差异。最终的动机是，了解系统的组成部分如何在不同状态下整体组织，将允许改进材料设计和控制，利用这些状态之间的接近和相互作用。在一个平行项目中，PI计划研究一类超导体的霍尔热传输机制，这些超导体与简单的元素超导体相比具有不同寻常的性质。材料在磁场作用下发生霍尔输运，使样品在垂直于磁场方向上产生温差。对超导体中这种类型的热传输的实验测量结果进行分析和解释，可以帮助研究人员区分导致超导性的各种可能机制，并澄清它们之间的竞争程度。此外，该项目将通过参与前沿研究来培训和指导青年科学家。该奖项还支持维基教科书项目的延续，该项目提供由学生根据教师课堂笔记编写的免费教科书。PI计划在这个项目的基础上进一步扩大到新的课程，成为传播科学知识的工具。该奖项支持理论研究和教育，旨在为相关量子凝聚态系统中一类难以理解的现象提供全面的理论描述，其中自发对称破缺，准粒子及其拓扑结构是密不可分的。这些项目涉及对理论模型的分析和数值工作，这些模型显示了自发对称性破缺成相关非超导状态的同等倾向，以及在后者附近出现的非常规超导状态。此外，它还探索了Berry相作为非朗道准粒子热霍尔输运的新机制，目的是开发一种可靠的工具，从实验数据中提取有价值的光谱信息。其中的目标是：确定具有不同配对对称性的非常规超导体混合态准粒子波函数的Berry曲率的能量分布；确定控制最近发现的热霍尔电导率的热激活尺度的物理过程，否则可能是无间隙系统；发展捕捉强相关性的涡旋核模型；建立一种理论，允许研究具有多种干扰有序倾向的模式系统中高于和低于转变温度的物理状态；探究了电荷载流子掺杂对蜂窝单分子层上狄拉克半金属与反铁磁绝缘体过渡相关量子临界点的影响；物理驱动系统中二维和三维二次带接触理论的进一步发展。所有这些项目的方法都涉及到量子多体和/或场论的分析和数值方法的结合。该奖项还支持维基教科书项目的延续，该项目提供由学生根据教师课堂笔记编写的免费教科书。PI计划在这个项目的基础上进一步扩大到新的课程，成为传播科学知识的工具。