Frustrated Magnets and Unconventional Superconductors: Symmetry and Quantum Mechanics

受阻磁体和非常规超导体：对称性和量子力学

• 批准号: RGPIN-2014-05717
• 负责人: Curnoe, Stephanie
• 金额: $ 2.26万
• 依托单位: Memorial University of Newfoundland
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=567345
• 关键词: Frustrated; Magnets; Unconventional; Superconductors; Symmetry

The proposed research will address fundamental problems in frustrated magnets and unconventional superconductors. I will use novel, symmetry-based analytic and computational methods to investigate systems whose phenomenology are long-standing puzzles. Geometrically frustrated magnets are materials with magnetic ions arranged in lattices of triangles or tetrahedra. Quantum mechanical effects arise when the degeneracy of magnetic states of each magnetic ion is small (of the order of two). Quantum frustrated magnets exhibit a variety of interesting phenomena, including "quantum spin liquids". The proposed research aims to advance the field of frustrated quantum magnets by resolving outstanding problems, such as determining the conditions under which as quantum spin liquid can exist. The short-term objectives of this program include the derivation of quantitative models of quantum magnets and calculations of physical properties of quantum magnets. Different analytic and computational approaches will be used to study these problems, including innovative applications of group theory (symmetry) methods. This program of research will develop original methods of analysis that will result in quantitative descriptions of quantum magnets. Quantum magnets and quantum materials in general are topics that are currently of high interest in Canada because of their potential technological applications and because of the challenging, fundamental questions they raise; the results of this program will contribute significantly to this branch of knowledge. Unconventional superconductors are those superconductors for which, in addition to gauge symmetry breaking, the point group symmetry and/or time reversal symmetry are also broken. My primary interests are the identification of the symmetry of unconventional superconductors and the exploitation of their unusual quantum mechanical properties. I propose to examine several specific systems, including the new family of iron-based superconductors and the rapidly growing collection of non-centrosymmetric superconductors. Physical properties, such as elastic moduli, conductivity, heat capacity, penetration depth and point contact conductance, will be calculated in order to make quantitative comparisons between theoretical models and experimental results. Superconductors may be coupled to normal metals or insulators either by point contact tunneling or proximity effect. Unconventional superconductors feature unusual spin-dependent currents in these set-ups. This work also seeks to find applications of such set-ups, such as the construction of a topological superconductor. This research will be a thorough investigation of unconventional superconductors and original applications of them. Canada has a strong tradition of superconductivity research that has resulted in many significant accomplishments. The proposed research will augment this effort and help Canada stay in the forefront of this area of research.

拟议中的研究将解决受抑磁体和非常规超导体的基本问题。我将使用新颖的，基于量子力学的分析和计算方法来研究其现象学是长期存在的难题的系统。几何阻挫磁体是磁性离子排列在三角形或四面体晶格中的材料。当每个磁性离子的磁态的简并度很小（大约为2）时，就会产生量子力学效应。量子受抑磁体表现出各种有趣的现象，包括“量子自旋液体”。这项研究旨在通过解决悬而未决的问题来推进受抑量子磁体领域，例如确定量子自旋液体可以存在的条件。该计划的短期目标包括量子磁体的定量模型的推导和量子磁体的物理性质的计算。不同的分析和计算方法将用于研究这些问题，包括群论（对称性）方法的创新应用。该研究计划将开发原始的分析方法，从而对量子磁体进行定量描述。量子磁体和量子材料一般是目前在加拿大高度感兴趣的主题，因为它们的潜在技术应用，因为它们提出的具有挑战性的基本问题;该计划的结果将大大有助于知识的这一分支。非常规超导体是指除了规范对称性破缺之外，点群对称性和/或时间反演对称性也被破缺的超导体。我的主要兴趣是识别非常规超导体的对称性和利用其不寻常的量子力学性质。我建议研究几个特定的系统，包括铁基超导体的新家族和快速增长的非中心对称超导体的集合。物理性能，如弹性模量，导电性，热容，渗透深度和点接触电导，将被计算，以使理论模型和实验结果之间的定量比较。超导体可以通过点接触隧穿或邻近效应与普通金属或绝缘体耦合。非传统超导体在这些装置中具有不寻常的自旋相关电流。这项工作也试图找到这样的设置的应用，如拓扑超导体的建设。这项研究将是对非常规超导体及其原始应用的彻底调查。加拿大在超导研究方面有着悠久的传统，取得了许多重大成就。拟议的研究将加强这一努力，并帮助加拿大保持在这一研究领域的前沿。