Quasiparticle Scattering and Tunneling Spectroscopic Studies on Kondo Lattices, Topological Insulators and Superconductors

* 非技术性摘要 * 理解新的电子态是如何出现的已经成为凝聚态物理学的一个中心研究课题。确定这种电子物质的组织原则将有助于发现具有新颖和有用功能的材料。这个项目的目标是在两个不同的场所研究这个主题：近藤晶格和拓扑材料。近藤晶格中的定域态与巡游电子的纠缠导致了一种新的电子态，在低温下具有极大的增强质量。这个过程是如何发生的，以及它与进一步过渡到有序状态的关系将被详细研究。为此，将采用测量技术来探测电子波如何在这样的系统中干涉。新的电子状态，称为拓扑，不能连续转换为普通状态，可以存在于某一类材料中，并且它们被认为表现出奇异的特性，例如在它们的边界上导电而不耗散，同时表现为绝缘体以通过体传输。在这个项目中，在这些拓扑状态和难以捉摸的马约拉纳粒子中诱导的超导性的性质可能有助于在未来建立量子计算机，将使用类似的测量技术进行探索。研究生和本科生将参加该项目，进行实验和数据分析，并参加研讨会/会议，以传播结果。技术摘要 * 近年来，人们对理解新量子物质的组织原理的兴趣重新燃起。本计画的目的在于揭示近藤晶格与拓扑材料中涌现现象的潜在机制。URu 2Si 2中隐藏的有序相长期以来一直无法明确确定其有序参数。为了解决这个问题，详细的本地化状态和巡回带之间的杂交过程和它的关系，隐藏的顺序过渡将使用光谱技术，如准粒子散射和隧道。其他密切相关的近藤晶格系统也将进行研究。由于非常规能带结构和费米面拓扑结构的共同作用，出现了新的拓扑电子态。了解它们的物理基础是一个前沿研究课题。在这个项目中，邻近诱导超导性的拓扑材料和马约拉纳费米子预测存在于这样的系统的性质将使用隧道光谱和其他相敏测量探测。研究生和本科生将参加该项目，进行实验和数据分析，并参加研讨会/会议，以传播结果。

****NON-TECHNICAL ABSTRACT****Understanding how novel electronic states emerge has become a central research topic in condensed matter physics. Identifying the organizing principles for such electronic matter will facilitate discovering materials with novel and useful functionalities. The goal of this project is to investigate this theme in two separate venues: Kondo lattices and topological materials. An entanglement of localized states with itinerant electrons in a so-called Kondo lattice leads to a novel electronic state with greatly enhanced mass at low temperature. How exactly this process occurs and its relationship to a further transition into an ordered state will be studied in detail. For this purpose, measurement techniques to probe how electron waves interfere in such a system will be employed. Novel electronic states, called topological, that cannot be continuously transformed to ordinary states can exist in a certain class of materials and they are known to exhibit exotic properties, such as conducting electricity on their boundaries without dissipation while behaving as insulators for transport through the bulk. In this project, the nature of superconductivity induced in these topological states and the elusive Majorana particles that could potentially help in building a quantum computer in the future, will be probed using similar measurement techniques. Graduate and undergraduate students will take parts in this project by carrying out experiments and data analysis and attending workshops/conferences to disseminate the results.****TECHNICAL ABSTRACT****Recent years have witnessed resurging interest in understanding the organizing principles for novel quantum matter. This project aims at unraveling the underlying mechanism for emergent phenomena in Kondo lattices and topological materials. The hidden order phase in URu2Si2 has long defied an unambiguous determination of its order parameter. Towards resolving this problem, the detailed hybridization process between localized states and itinerant bands and its relationship to the hidden order transition will be investigated using spectroscopic techniques such as quasiparticle scattering and tunneling. Other closely related Kondo lattice systems will also be studied. Novel topological electronic states emerge due to a combined effect of unconventional band structure and Fermi surface topology. Understanding their underlying physics is a frontier research topic. In this project, the nature of proximity-induced superconductivity in topological materials and Majorana fermions predicted to exist in such systems will be probed using tunneling spectroscopy and other phase-sensitive measurements. Graduate and undergraduate students will take parts in this project by carrying out experiments and data analysis and attending workshops/conferences to disseminate the results.