Microwave spectroscopy of unconventional metals, superconductors and insulators

非常规金属、超导体和绝缘体的微波光谱

• 批准号: 261622-2013
• 负责人: Broun, David
• 金额: $ 2.99万
• 依托单位: Simon Fraser University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=633517
• 关键词: Microwave; spectroscopy; unconventional; metals; superconductors

Society is currently reaping the benefits of the revolution in semiconductor electronics that occurred after the quantum behaviour of noninteracting electrons was understood in the early 20th century. It is the hope of many researchers around the world that there will be a second revolution in electronic materials when we understand a far more difficult quantum problem - the behaviour of systems of strongly interacting electrons. At this stage the challenges are fundamental: to understand how the important electronic properties emerge in systems of interacting electrons, and to harness these materials so that they produce the desired properties in a controlled way. Many of these materials display unusual forms of superconductivity, a state of matter in which all electrical resistance vanishes. Examples include the cuprate high temperature superconductors; the so-called "heavy fermion" materials, in which electrons appear to be 100 to 1000 times heavier than normal; and the recently discovered iron-based superconductors. At present, the mechanism responsible for superconductivity is not well understood in any of these materials. In addition, the nonsuperconducting states are unusual metals that pose some of the greatest challenges to our understanding of electrons in solids. Our research group has set up a novel facility for carrying out microwave spectroscopy of these materials that is the only one of its kind in the world. Measurements can be performed at temperatures down to 0.05 K, in magnetic fields up to 9 tesla, and at frequencies up to 25 GHz. Microwave fields are used to accelerate the electrons in order to probe their inertial response; and to study their collisions with impurities and with one another. Using this information we are able to understand the structure and dynamics of these novel electronic states. We are also developing new experimental tools, including systems for detecting and quantifying subtle signs of time-reversal-symmetry breaking, an effect that has important applications in magnetism, semiconductors, unconventional superconductors, and so-called topological insulators - materials that are electrically insulating in the bulk, but form robust and highly conducting surface states.

当前，社会正在从20世纪初期了解非互动电子量子行为后发生的半导体电子革命的好处。世界上许多研究人员的希望是，当我们理解一个更加困难的量子问题 - 强烈相互作用的电子系统的行为时，电子材料将进行第二次革命。在此阶段，挑战是基本的：了解相互作用的系统系统中重要的电子特性如何出现，并利用这些材料以控制方式产生所需的性质。这些材料中的许多表现出异常形式的超导性，这是所有电阻消失的物质状态。例子包括高温高温超导体；所谓的“重费式”材料，其中电子似乎比正常人重100至1000倍。以及最近发现的基于铁的超导体。目前，这些材料中的任何一种尚未充分了解负责超导性的机制。此外，非耐受性状态是异常的金属，它对我们对固体中电子的理解构成了一些最大的挑战。我们的研究小组建立了一个新颖的设施，用于对这些材料进行微波光谱，这是世界上唯一的一种。可以在低至0.05 K的温度，最多9特斯拉的磁场和最高25 GHz的频率下进行测量。微波场用于加速电子，以探测其惯性反应。并与杂质和彼此一起研究他们的碰撞。使用这些信息，我们能够理解这些新型电子状态的结构和动力学。我们还正在开发新的实验工具，包括用于检测和量化时间逆转对称性破坏的细微迹象，这种效果在磁性，半导体，半导体，非常规的超导体以及所谓的拓扑绝缘子中具有重要的应用，以及在体积中且形成稳健的表面状态和高度传导状态的材料。