Electronic Structure of Unconventional Spin-Orbit Materials

非常规自旋轨道材料的电子结构

• 批准号: 1507585
• 负责人: M. Zahid Hasan
• 金额: $ 39.32万
• 依托单位: Princeton University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2018-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1507585&HistoricalAwards=false
• 关键词: Electronic; Structure; Unconventional; Spin; Orbit

Nontechnical Abstract: In an ordinary insulator, such as diamond, the occupied electronic levels are separated from unoccupied levels by a large energy barrier known as an energy gap. The energy gap prevents current flow when an electric field is applied. Recent research has uncovered a new class of insulators, called topological insulators and related Dirac materials, in which electrons can bypass the energy gap by moving out to the surfaces of the insulator. The energy vs. velocity behavior of these unusual electrons moving on the surface is light-like and follows Dirac equation. They exhibit many unusual quantum properties which can be harnessed to improve spin-based electronics, novel forms of quantum computing and energy-efficient devices in the longer run. This project focuses on studying the details of the novel quantum behaviors of electrons moving on the surface which will in turn not only lead to better understanding of the mechanism for doing so but also likely discover new pathways to applications. Students working on this project develop expertise in vacuum and nano-technology, material characterization methodologies, and advanced x-ray optics and electronic spectroscopy techniques preparing them for scientific careers in industry, academia or government laboratories. Outreach programs "Quantum Materials" and their integration with Princeton's REU and others such as "The Leadership Alliance Program: dedicated to increase diversity in academia" involve many minority and young students and facilitate their entry into the exciting world of modern science.Technical Abstract: Discovering new phases of matter with useful electronic or magnetic properties is an important goal in modern physics. In the past few years, research has uncovered a new phase of Dirac material dubbed "Topological Insulators". They exhibit quantum Hall-like effects without magnetic field and can be operated at room temperatures. In a topological insulator, these effects lead to surface states that have unusual spin textures with a linear relationship between energy and momentum (Dirac dispersion). Such states have been predicted to give rise to dissipationless (energy saving) spin currents, quantum entanglements and novel macroscopic behavior that obeys axionic electrodynamics rather than Maxwell's equations and can potentially realize exotic particles that can be used for fault tolerant quantum computing. Angle-resolved photoemission spectroscopy is used to study the quantum properties of several Bi-based 2D and 3D Dirac materials and their magnetic and superconducting doping-induced interaction and correlation effects under this project. When new materials with similar properties are discovered they are also studied in concert and compared with previously known materials. Students working on this project develop expertise in vacuum and nano-technology, material characterization methodologies, and advanced x-ray optics and spin- and photon-polarization resolved electronic spectroscopy techniques preparing them for future scientific careers in industry, academia or government laboratories. Outreach programs "Quantum Materials" and their integration with Princeton's REU and others such as "The Leadership Alliance Program: dedicated to increase diversity in academia" involve many minority and young students and facilitate their entry into the exciting world of modern science.

非技术摘要：在普通的绝缘体中，例如金刚石，被占据的电子能级与未被占据的能级被称为能隙的大能量势垒分开。当施加电场时，能隙阻止电流流动。最近的研究发现了一类新的绝缘体，称为拓扑绝缘体和相关的狄拉克材料，其中电子可以通过移动到绝缘体的表面来绕过能隙。这些不寻常的电子在表面上运动的能量-速度行为是类光的，并遵循狄拉克方程。它们表现出许多不寻常的量子特性，可以利用这些特性来改善基于自旋的电子学，量子计算的新形式和长期的节能设备。该项目的重点是研究电子在表面上移动的新量子行为的细节，这不仅会导致更好地理解这样做的机制，而且可能会发现新的应用途径。从事该项目的学生将发展真空和纳米技术，材料表征方法以及先进的X射线光学和电子光谱技术方面的专业知识，为他们在工业，学术界或政府实验室的科学事业做好准备。“量子材料”的拓展项目及其与普林斯顿大学的REU和其他项目的整合，如“领导联盟项目：致力于增加学术界的多样性”，涉及许多少数民族和年轻学生，并促进他们进入令人兴奋的现代科学世界。技术摘要：发现具有有用的电子或磁性的物质的新相是现代物理学的一个重要目标。在过去的几年里，研究发现了狄拉克材料的一个新阶段，称为“拓扑绝缘体”。它们在没有磁场的情况下表现出量子霍尔效应，并且可以在室温下工作。在拓扑绝缘体中，这些效应导致表面态具有不寻常的自旋纹理，能量和动量之间具有线性关系（狄拉克色散）。这种状态已经被预测会产生无耗散（节能）的自旋电流，量子纠缠和新的宏观行为，服从公理电动力学，而不是麦克斯韦方程，并可能实现奇异粒子，可用于容错量子计算。本项目利用角分辨光电子能谱研究了几种Bi基二维和三维Dirac材料的量子特性及其磁和超导掺杂诱导的相互作用和关联效应。当发现具有类似性质的新材料时，它们也会被一起研究，并与以前已知的材料进行比较。从事该项目的学生发展真空和纳米技术，材料表征方法，先进的X射线光学和自旋和光子偏振分辨电子光谱技术的专业知识，为他们未来在工业，学术界或政府实验室的科学事业做好准备。外展计划“量子材料”及其与普林斯顿大学的REU和其他如“领导联盟计划：致力于增加学术界的多样性”的整合涉及许多少数民族和年轻学生，并促进他们进入现代科学的令人兴奋的世界。