Topological Electronic Structure in Strong Spin-Orbit Coupled Materials

技术摘要：发现具有有用的电子或磁性质的新相是现代物理学的一个重要目标。在过去的几年里，研究发现了量子物质的一个新阶段，被称为“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，可以在室温下操作。在拓扑绝缘体中，这些效应导致表面态具有不寻常的自旋织构，并且在能量和动量之间具有线性关系（狄拉克色散）。据预测，这种状态会产生无耗散（节能）的自旋电流、量子纠缠和新的宏观行为，这些行为服从轴子电动力学而不是麦克斯韦方程组，并且有可能实现可用于容错量子计算的奇异粒子。角分辨光谱学将用于研究几种新型拓扑绝缘体的量子特性。参与该项目的学生将在真空和纳米技术、材料表征方法、先进的x射线光学、自旋和光子偏振分辨电子光谱技术等方面发展专业知识，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。外展项目“量子材料”和“诺贝尔科学-今年”展览，以及它们与普林斯顿大学的“领导联盟计划：致力于增加学术界的多样性”的整合，将吸引许多少数民族和年轻学生，并促进他们进入现代科学的世界。非技术摘要：在普通绝缘体中，如金刚石，被称为能隙的大能量势垒将占据的电子能级与未占据的电子能级分开。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，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与速度的关系类似于光。它们表现出许多不同寻常的量子特性，可以用来改进基于自旋的电子学、新型量子计算和节能设备。该项目将专注于研究电子在表面上移动的新量子行为的细节，这不仅会更好地理解这种行为的机制，而且可能会发现新的应用途径。参与该项目的学生将在真空和纳米技术、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发展专业知识，为他们在工业、学术界或政府实验室的科学事业做好准备。外展项目“量子材料”和“诺贝尔科学-今年”展览，以及它们与普林斯顿大学的“领导联盟计划：致力于增加学术界的多样性”的整合，将吸引许多少数民族和年轻学生，并促进他们进入现代科学的世界。

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 quantum matter 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 will be used to study the quantum properties of several novel topological insulators under this project. Students working on this project will 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 "Nobel-Science-This-Year" expositions and their integration with Princeton's "The Leadership Alliance Program: dedicated to increase diversity in academia" will involve many minority and young students and facilitate their entry into the world of modern science.Non-Technical 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, 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. They exhibit many unusual quantum properties which can be harnessed to improve spin-based electronics, novel forms of quantum computing and energy-efficient devices. This project will focus 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 will 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 "Nobel-Science-This-Year" expositions and their integration with Princeton's "The Leadership Alliance Program: dedicated to increase diversity in academia" will involve many minority and young students and facilitate their entry into the world of modern science.