Emergent Quantum Phenomena in Topological Kondo Insulators

拓扑近藤绝缘体中的涌现量子现象

• 批准号: 1410665
• 负责人: richard greene
• 金额: $ 42万
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-08-01 至 2018-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1410665&HistoricalAwards=false
• 关键词: Emergent; Quantum; Phenomena; Topological; Kondo

Non-Technical AbstractThis award from the Condensed Matter Physics program of the Division of Materials Research supports research on the electronic properties of a new class of material known as Topological Insulators. A topological insulator is an unusual quantum state in which the bulk of the material is an electrical insulator, while the surface is a conductor that is stable against various external perturbations. Topological insulators have generated great scientific excitement over the past few years because of the novel electrical properties and their potential application as advanced electronic devices in areas such as quantum computation and spin transport. However, all of the materials discovered to date have a non-insulating bulk transport behavior because of unavoidable defects in the material; therefore, they do not exhibit ideal or useful topological properties. A recent theory has suggested that a special class of material, known as a Kondo insulator, would be a topological insulator with a true bulk insulating state. Researchers at the University of Maryland conduct measurements of the electronic properties of known Kondo insulators to investigate their possible topological behavior and to test their suitability for new and novel electronic applications. This research project involves the training of undergraduate and graduate students in advanced measurement techniques and in cutting edge scientific knowledge of materials physics.Technical AbstractResearchers at the University of Maryland are undertaking experimental studies of electronic transport phenomena in different Kondo insulator systems that are theoretically suggested to harbor topological surface states. Understanding the novel properties of topological insulators and the role of strong electron correlations on topological properties is a major basic science problem in condensed matter physics. The recent discovery of a surface metallic state in the Kondo insulator SmB6 suggests that strongly correlated TIs may exist. However, despite many unconventional transport phenomena recently found in SmB6, the "smoking gun" evidence for a nontrivial topological surface state has yet to been established. This study emphasizes the transport properties of thin films and single crystals at low temperatures (down to 20 mK), where novel emergent quantum phenomena are expected to be prominent. The project uses point contact spectroscopy, static electric field effect studies, and high magnetic field transport measurements and microwave and optical measurements on promising KI materials. An important thrust of this project is the study of the proximity effect, since it has been predicted that incorporating topological insulators with ferromagnetic insulators and/or conventional superconductors may lead to exotic properties such as Majorana fermion excitations. All the materials required for these measurements are being synthesized and characterized in-house. This research project involves the training of undergraduate and graduate students in advanced measurement techniques and in cutting edge scientific knowledge of materials physics.

材料部凝结物理学计划的非技术抽象奖支持对新型材料的电子特性的研究，称为拓扑绝缘子。拓扑绝缘子是一种不寻常的量子状态，其中大部分材料是电绝缘体，而表面是对各种外部扰动稳定的导体。在过去的几年中，拓扑绝缘子在过去几年中引起了极大的科学兴奋，因为新型电气性能及其在量子计算和自旋传输等领域的高级电子设备的潜在应用。但是，由于材料中不可避免的缺陷，迄今为止发现的所有材料都具有不可构造的批量运输行为。因此，它们没有表现出理想或有用的拓扑特性。最近的一种理论表明，一种特殊的材料（称为围绕的绝缘子）将是具有真正散装绝缘状态的拓扑绝缘子。马里兰州大学的研究人员对已知的近藤绝缘体的电子特性进行了测量，以研究其可能的拓扑行为并测试其对新型和新型电子应用的适用性。该研究项目涉及对高级测量技术的本科生和研究生的培训。马里兰州大学的技术抽象探索者正在对不同的近kondo绝缘体系统中的电子传输现象进行实验研究，从理论上讲是象征着象征着象征性表面状态的。了解拓扑绝缘子的新特性以及强电子相关性在拓扑特性中的作用是凝聚态物理学的主要基础科学问题。 最近发现的近托绝缘子SMB6中表面金属状态的发现表明，可能存在密切相关的TI。然而，尽管最近在SMB6中发现了许多非常规的运输现象，但尚未确定非平凡拓扑表面状态的“吸烟枪”证据。 这项研究强调了薄膜和单晶在低温下（降至20 mk）的运输特性，在这种情况下，新型新兴量子现象预计将是突出的。 该项目使用点接触光谱，静态电场效应研究以及高磁场传输测量以及对有希望的KI材料的微波和光学测量。该项目的一个重要作用是对接近性效应的研究，因为已经预测，将拓扑绝缘子与铁磁绝缘子和/或常规超导体结合起来可能会导致诸如Majorana fermion兴奋之类的外来特性。这些测量所需的所有材料都被合成和内部表征。该研究项目涉及对高级测量技术的本科和研究生的培训，以及材料物理学的尖端科学知识。