Topology, interactions, and disorder in exotic quantum materials

奇异量子材料中的拓扑、相互作用和无序

• 批准号: RGPIN-2020-06999
• 负责人: Maciejko, Joseph
• 金额: $ 4.44万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=741535
• 关键词: Topology; interactions; disorder; exotic; quantum

Ordinary phases of matter-solid, liquid, and gas-are distinguished by emergent macroscopic properties, such as rigidity or the lack thereof, which are a consequence of how atoms microscopically arrange themselves, but also transcend the minute details of such arrangements. At temperatures near absolute zero, quantum effects allow for qualitatively new patterns of microscopic arrangements that produce novel emergent properties beyond those of ordinary matter, such as superfluidity, magnetism, and superconductivity. The field of quantum materials, a key subdiscipline of condensed matter physics, attempts to theoretically understand such quantum phases of matter and the transitions between them, and to experimentally discover materials that realize them. In the past ten years or so, this field has witnessed a veritable revolution. Recognized in part by the 2016 Nobel Prize in Physics, the prediction of topological insulators-where an insulating bulk coexists with a robust metallic surface-has received wide experimental confirmation and evolved into a thriving branch of mainstream condensed matter physics. The discovery of exotic magnetic materials where quantum "fuzziness" is so strong as to completely demagnetize them may signal the long-awaited discovery of the spin liquid, an exotic quantum state of matter first theorized in the 1970s. The unusual behavior of ultrathin materials in strong magnetic fields reveals new cooperative behaviors previously thought impossible, such as the emergence of collective excitations with only a fraction of the charge of an electron. Many of the unusual properties of those exotic quantum materials, such as metallic surface states and fractionalized excitations, may lead to novel technological applications in low-power electronics and quantum computing. A necessary first step towards such applications, the development of a complete theoretical understanding of this bewildering variety of new phenomena is however hindered by the lack of a unified conceptual framework and complicated by the unavoidable presence of imperfections and impurities in real materials. Supported in part by this NSERC Discovery Grant, my research program aims to achieve a deeper and more unified understanding of three broad classes of quantum materials-topological materials, spin liquids, and ultrathin materials in high magnetic fields-through the construction of mathematical models that incorporate both quantum effects and material imperfections, and the analysis of those models via cutting-edge theoretical methods. By training undergraduate research assistants (URAs), graduate students, and postdoctoral fellows (PDFs) in a wide range of broadly applicable analytical and computational skills, this research will help maintain Canada's leadership in the field of quantum materials and will contribute to grow our country's knowledge-based economy.

物质的普通相--固体、液体和气体--通过涌现的宏观性质来区分，例如刚性或刚性的缺乏，这是原子如何在微观上排列自己的结果，但也超越了这种排列的微小细节。在接近绝对零度的温度下，量子效应允许微观排列的质的新模式，产生超越普通物质的新的涌现性质，如超流性，磁性和超导性。量子材料领域是凝聚态物理学的一个关键分支学科，试图从理论上理解物质的量子相及其之间的跃迁，并通过实验发现实现它们的材料。在过去的十多年里，这一领域经历了一场名副其实的革命。2016年诺贝尔物理学奖部分认可了拓扑绝缘体的预测-绝缘体与坚固的金属表面共存-已经得到了广泛的实验证实，并发展成为主流凝聚态物理学的一个蓬勃发展的分支。奇异磁性材料的发现，其中量子“fuselage”是如此之强，完全退磁，可能标志着人们期待已久的发现自旋液体，一个奇异的量子态的物质首先在20世纪70年代的理论。量子材料在强磁场中的不寻常行为揭示了以前认为不可能的新的合作行为，例如电子的一小部分电荷出现集体激发。这些奇异量子材料的许多不寻常性质，例如金属表面态和分数激发，可能会导致低功率电子学和量子计算的新技术应用。然而，对这种令人困惑的各种新现象的完整理论理解的发展，是走向这种应用的必要的第一步，却因缺乏统一的概念框架而受到阻碍，并因真实的材料中不可避免地存在缺陷和杂质而变得复杂。在NSERC发现资助的部分支持下，我的研究计划旨在通过构建包含量子效应和材料缺陷的数学模型，并通过尖端理论方法分析这些模型，对三大类量子材料-拓扑材料，自旋液体和高磁场中的自旋材料-进行更深入，更统一的理解。通过培训本科研究助理（URA），研究生和博士后研究员（PDF）广泛适用的分析和计算技能，这项研究将有助于保持加拿大在量子材料领域的领导地位，并将有助于发展我国的知识经济。