Proximity effects in topological insulators

最近的实验进展和激增的兴趣在电输运检测的自旋-轨道诱导自旋-动量锁定的动机，我们建议进行系统和全面的第一性原理计算的邻近效应在3D拓扑绝缘体，侧重于Bi 2Se 3家庭，但也对一些新的结构。特别是，我们计划建立狄拉克能带结构的修改，并提取相关的邻近交换和自旋轨道耦合出现在所研究的材料的表面状态。我们将使用常见的铁磁体和隧道势垒模型结拓扑绝缘体，并评估不同的结材料成分和隧道势垒厚度所造成的邻近效应。我们还预计强磁各向异性的邻近效应。为了补充第一原理计算，我们将建立现实的最小唯象模型，基于对称性参数，以适应和描述的邻近带结构，使大规模的数值模型磁输运电荷和自旋计算拓扑绝缘体与邻近区域由于铁磁电极。无论是第一性原理和模型模拟将提供定性的见解和定量信息的重要表面态自旋和电荷输运。我们还希望，我们的工作将澄清一些紧迫的未解决的问题，重要的解释最近的实验，以及激励和指导新的实验，通过预测最佳材料和结构参数的自旋注入和检测，自旋转移力矩现象。

Motivated by the recent experimental progress and surge of interest in the electrical transport detection of the spin-orbit induced spin-momentum locking, we propose to perform systematic and comprehensive first-principles calculations of the proximity effects in 3d topological insulators, focusing on the Bi2Se3 family, but also on some novel structures. In particular, we plan to establish modifications to the Dirac band structures and extract relevant proximity exchange and spin-orbit couplings emergent in the surface states of the investigated materials. We will use common ferromagnets and tunnel barriers to model junctions with topological insulators, and evaluate the proximity effects caused by different junction materials compositions and tunnel barrier thicknesses. We also expect strong magnetoanisotropies of the proximity effects. To supplement the first-principles calculations, we will build realistic minimal phenomenological models, based on symmetry arguments, to fit and describe the proximity band structures, enabling large-scale numerical model magneto-transport charge and spin calculations for topological insulators with proximity regions due to ferromagnetic electrodes. Both the first-principles and model simulations will provide qualitative insights and quantitative information important for surface states spin and charge transport. We also expect that our work will clarify some pressing unresolved issues important for the interpretation of recent experiments as well as motivate and guide new experiments by predicting optimal materials and structural parameters for spin injection and detection, and spin-transfer torque phenomena.