Nanoscale Studies of Topological Insulators

拓扑绝缘体是一类新发现的具有绝缘体态和金属表面态的材料。这些材料的表面态是手性的和自旋极化的，因此不受反向散射的影响。这些材料中表面态的自旋结构和拓扑性质使它们成为研究磁性、拓扑超导性和奇异粒子的新场所，另一方面，实现无耗散自旋输运和拓扑量子计算。该奖项将支持低温扫描隧道显微镜（STM）拓扑绝缘体（Bi 2X 3类）的光谱学（STS）研究。拓扑表面态的自旋织构将使用亚开尔文STM和自旋极化STM结合双轴高场磁体进行研究。准粒子干涉是一种成熟的STS技术，将用于确定感兴趣的物理量，例如表面态的费米速度和g因子。用磁性杂质的体和表面掺杂将用于研究这些表面状态与磁性的相互作用。体嵌入和外延薄膜生长将用于寻找与超导性的拓扑相互作用。该奖项将支持两名研究生的教育和培训，并将通过理论和互补实验技术的合作创造丰富的知识环境。*每隔几年就会发现一类新的材料，并以其新颖的物理和技术前景席卷科学界。2009年，拓扑绝缘体的发现引起了这样的涟漪。拓扑绝缘体（TI）是其内部的电绝缘体。然而，在其表面上，它不仅是一种电荷自由移动的金属，而且是一种特殊的金属，在这种金属中，这些电荷被阻止反向散射，从而消除了微电子中的主要耗散和加热源。这些特性使TI成为实现两项未来技术的有希望的候选者：自旋电子学，一种非常低功率的传统电子学替代品，以及量子计算，一种快速解决计算密集型问题的变革方法。该奖项将支持使用扫描隧道显微镜-在原子尺度上映射电子行为的仪器-对拓扑绝缘体的研究。像这样的表面敏感探针非常适合研究这些材料的新表面特性。在理论和其他实验技术的合作下，将评估这些和其他新技术的路径。

Technical AbstractTopological insulators are a newly discovered class of materials with insulating bulk states and metallic surface states. The surface states are chiral and spin-polarized, and therefore protected from backscattering.The spin structure and topological nature of the surface states in these materials make them a novel playground for studying magnetism, topological superconductivity and exotic particles on the one hand, and enabling dissipationless spin transport and topological quantum computing on the other.This award will support low temperature scanning tunneling microscopy (STM) and spectroscopy (STS) studies on topological insulators (Bi2X3 class). The spin texture of the topological surface states will be studied using a sub-Kelvin STM and spin-polarized STM in conjunction with two-axis high-field magnets. Quasiparticle interference, an established STS technique, will be used to determine physical quantities of interest, e.g. the Fermi velocity and g-factor of surface states. Bulk and surface doping with magnetic impurities will be used to study the interplay of these surface states with magnetism. Bulk intercalation and epitaxial film growth will be used to look for topological interactions with superconductivity.The award will support the education and training of two graduate students and will create a rich intellectual environment through collaborations with theory and complementary experimental techniques.**************************************************Non-Technical AbstractEvery few years a new class of materials is discovered and takes the scientific world by storm with novel physics and technological promise. In 2009, the discovery of topological insulators created one such ripple. A topological insulator (TI) is an electrical insulator in its interior. On its surface, however, it is not only a metal with charges free to move, but a special metal where those charges are prevented from backscattering, removing the primary source of dissipation and heating in microelectronics. These properties make TIs promising candidates for enabling a couple of futuristic technologies: spintronics, a very low power replacement for conventional electronics, and quantum computing, a transformational method of rapidly solving computationally intensive problems.This award will support studies of topological insulators using scanning tunneling microscopes - instruments that map electronic behavior at the atomic scale. Surface-sensitive probes like these are ideally suited to study the novel surface properties of these materials. In collaboration with theory and other experimental techniques, the path toward these and other new technologies will be assessed.