DMREF: Collaborative Research: Discovering Insulating Topological Insulators

DMREF：协作研究：发现绝缘拓扑绝缘体

• 批准号: 1534734
• 负责人: Daniel Dessau
• 金额: $ 30万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2019-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1534734&HistoricalAwards=false
• 关键词: DMREF; Collaborative; Research; Discovering; Insulating

Non-technical abstract:At the heart of electronic devices lies silicon, a semiconductor material that can be madepure enough for high performance and is amenable to mass production. While suchcircuitry is continually improving, silicon is unable to exhibit quantum phenomenarequired for complete solutions in weather prediction, genomics, and secure encryption.A new class of materials, the so-called topological insulators, holds the promise torealize such phenomena and revolutionize computing. Topological insulators are, intheory, non-metallic in the interior of the material but behave like a metal at the surface.In addition, the quantum character of these metallic electrons can be switched, which isthe basic information processing function. While known topological insulatorsdemonstrate the metallic surface state, these materials have not been made pure enoughfor incorporating into electronic devices. Specifically, they are not yet insulating in theinterior. This project will seek to find new topological insulators and to engineer them tolevels of purity needed for an insulating interior and satisfy the performance demands ofelectronic circuits. The project will impact the electronics industry as well as traingraduates skilled in the computational and experimental techniques of this new class ofmaterials.Technical abstract:The goal of the project is to create topological insulator materials that are pure enough inthe bulk to exhibit true insulating behavior. Topological insulators are found amonghigh-Z atom containing semiconductors with band gaps small enough that the spin-orbitcoupling related to the large Z-number can invert the conduction and valence band.These materials must also possess spatial inversion symmetry for the relevant orbitals.The project will explore candidate materials classes among pseudo-binary andpyrochlore-related structures containing heavy metals such as Ir, Re, and Os. Materialssynthesis by solid state chemistry techniques will be guided by simulations based ondensity functional theory. Promising candidate materials will be synthesized in singlecrystal form by appropriate methods including vapor transport, zone refinement, andgrowth from flux. Crystalline specimens will be studied with angle resolvedphotoemission spectroscopy and conventional charge transport techniques. Prototypetransistor devices will be fabricated on a smaller subset of these systems. The results ateach measurement stage will be fed back to the theory and synthesis efforts.

非技术摘要：电子设备的核心是硅，这是一种半导体材料，其纯度足以实现高性能，并且适合大规模生产。虽然此类电路不断改进，但硅无法表现出天气预报、基因组学和安全加密等完整解决方案所需的量子现象。一类新型材料，即所谓的拓扑绝缘体，有望实现此类现象并彻底改变计算。拓扑绝缘体理论上在材料内部是非金属的，但在表面表现得像金属。此外，这些金属电子的量子特性可以切换，这是基本的信息处理功能。虽然已知的拓扑绝缘体表现出金属表面状态，但这些材料的纯度还不足以合并到电子设备中。具体来说，它们的内部尚未绝缘。该项目将寻求寻找新的拓扑绝缘体，并将其设计成绝缘内部所需的纯度水平，并满足电子电路的性能要求。该项目将影响电子行业，并培养熟练掌握此类新型材料的计算和实验技术的毕业生。技术摘要：该项目的目标是创造拓扑绝缘体材料，其体积足够纯净，能够表现出真正的绝缘行为。拓扑绝缘体存在于含高 Z 原子的半导体中，其带隙足够小，与大 Z 数相关的自旋轨道耦合可以反转导带和价带。这些材料还必须具有相关轨道的空间反演对称性。该项目将探索含有重金属（如铱、铼和锇）的伪二元和烧绿石相关结构的候选材料类别。固态化学技术的材料合成将以基于密度泛函理论的模拟为指导。有前景的候选材料将通过适当的方法以单晶形式合成，包括蒸气传输、区域细化和助熔剂生长。将使用角分辨光电子能谱和传统电荷传输技术来研究晶体样品。原型晶体管器件将在这些系统的较小子集上制造。每个测量阶段的结果将反馈给理论和综合工作。