Spin scattering of topologically protected electrons at defects

拓扑绝缘体（TI）领域正朝着两个方向发展：发现具有新拓扑概念的新材料，例如Weyl半金属，或在已知和研究的材料中的应用。本提案包括后一个方向的主题，重点是输运现象和自旋-电荷转换：埃德尔斯坦（磁电）效应，自旋-轨道扭矩，自旋泵，反常霍尔效应，和电位TI。输运现象总是与耗散和相位退相干效应有关。电荷或自旋输运过程中普遍存在的耗散源是杂质原子和其他缺陷的散射。我们从第一个资助期获得的杂质散射经验将在这里应用。我们在Bi 2 Te 3中的聚焦效应，通过费米表面嵌套的背散射的可能性，或通过掺杂改变费米表面来塑造散射特性的发现，所有这些都是应用和定制TI输运特性的丰富性和潜力的例子。通过玻尔兹曼型方程，从头计算的散射振幅和能带结构进入，我们将系统地研究潜在的应用，并给出实验指导。在社区中获得的经验表明，最流行的三维TI，Bi 2 Te 3和Bi 2Se 3，很好地描述了密度泛函理论，因此我们有信心在我们的方法。与此同时，我们将继续把我们的方法的核心，即散射振幅，通过比较准粒子干涉图案和电位计算与我们的实验同事的结果（P. Sessi/M. Bode，Y.安藤角博比施，B。Voigtländer）。

The field of Topological Insulators (TI) is growing in two directions: discovery of new materials with new topological concepts, e.g. Weyl semimetals, or applications in already known and investigated materials. The present proposal comprises topics in the latter direction with emphasis in transport phenomena and spin-charge conversion: Edelstein (magnetoelectric) effect, spin-orbit torque, spin pumping, anomalous Hall effect, and potentiometry on TI. Transport phenomena are always related to dissipation and phase decoherence effects. A ubiquitous source of dissipation during charge or spin transport is scattering off impurity atoms and other defects. Our gained experience on impurity scattering from the first funding period will be applied here.Our findings on the focussing effect in Bi2Te3, on the possibility of back-scattering via the Fermi Surface nesting, or on the shaping of the scattering properties by changing the Fermi surface via doping, all these are examples of the richness and potential for applications and for tailoring transport properties on TI. By means of Boltzmann-type equations, where the ab-initio-calculated scattering amplitude and band-structure enter, we will systematically investigate prospective applications and give guidelines to experiment. Experience gained in the community shows that the most popular three-dimensional TI, Bi2Te3 and Bi2Se3, are well described by density-functional theory, and therefore we have confidence in our approach. At the same time we will continue to bring the core of our method, i.e. the scatering amplitude, to test versus the experiment by comparing quasiparticle interference patterns and potentiometry calculations with the results of our experimental colleagues (P. Sessi/M. Bode, Y. Ando, C. Bobisch, B. Voigtländer).