Low-dimensional electronic magneto-transport in epitaxial ultra-thin Bi and Bi-Sb alloy films: impurities, structure, confinement and disorder.

我们对电子在表面和界面上的沿着自旋极化态的输运及其与它们的结构和缺陷的耦合在原子尺度上的知识仍然令人惊讶地不完整。因此，在本项目中，将研究具有不同磁矩的杂质在表面磁输运中的散射特性，这些杂质在单晶和外延生长的Bi膜上，以及在Bi-Sb合金上，由于Rashba效应而表现出强的电子相关性和强的自旋极化。由于铋锑合金开关在一定范围内的浓度到政权的拓扑绝缘体，我们将能够比较平凡和拓扑保护表面的表面电导特性。 在磁场中进行磁输运测量高达4 T，在5和300 K之间的温度范围内，再加上低能电子衍射（LEED），我们的目标是定量的杂质引起的表面电导的修改。因此，我们想澄清的相互依存关系，例如，杂质的局部磁矩、吸附位置的局部对称性、电荷转移和能带结构的改变，仅举几个相关的互连。我们将扩展研究，以测试这些概念的拓扑绝缘体表面的铋锑合金。特别是，我们将研究表面态电导的鲁棒性。最后，我们想通过生长不同表面取向的台阶薄膜（Bi（111），（110）和（221））来研究一维边缘态的散射特性。

Our knowledge of electronic transport along spin-polarized states at surfaces and interfaces and its coupling with their structure and with defects on the atomic scale is still surprisingly incomplete. Therefore, the scattering properties of impurities with various magnetic moments in surface magneto-transport will be investigated in this project on ultrathin crystalline and epitaxially grown Bi-films, and on Bi-Sb alloys, which exhibit strong electron correlation with strong spin polarization due to the Rashba effect. Since Bi-Sb alloys switch in a certain range of concentrations into the regime of topological insulators, we will be able to compare surface conductance properties of trivial and topologically protected surfaces. Carrying out magneto-transport measurements in magnetic fields up to 4 T and in the temperature range between 5 and 300 K, coupled with Low Energy Electron Diffraction (LEED), we aim at the quantification of impurity-induced modifications of surface conductance. Thus we want to clarify the interdependence of, e.g., local magnetic moments of impurities, local symmetry of adsorption sites, charge transfer, and modifications of band structure, just to name a few relevant interconnections. We will extend the studies to test these concepts for topological insulator surfaces in BiSb alloys. In particular we will study robustness of surface state conductance. Finally we want to study the scattering properties of one-dimensional edge states by growth of stepped films with various surface orientations (Bi(111), (110) and (221)).