Microscopic understanding of the current induced spin selectivity in chiral molecular systems

电流诱导的自旋选择性过程在手性分子体系中引起了广泛的关注，因为即使在环境条件下，电子沿着手性主结构的传播也会导致明显的自旋极化。尽管这种效应具有稳健性，但微观模型是不完整的，而且这种效应本身也没有被完全理解。在这里，我们提出了一种表面科学方法，利用扫描隧道显微镜在单分子分辨率的原子尺度上研究这种影响。多肽从溶液中吸附到磁性Au/Co/Au异质结构上，使我们能够定量地测量螺旋分子中的自旋极化。因此，本文利用α-螺旋型聚丙氨酸分子的柔韧性，系统研究其在分子和被吸附分子表面的输运，确定分子长度、序列、螺旋度、邻居数和耦合对被吸附手性分子邻近诱导的电流诱导分子自旋选择性和磁性的影响。

The current induced spin selectivity process in chiral molecular systems gathered a lot of interest, as the propagation of electrons along the chiral backbone structure results in a pronounced spin polarization even at ambient conditions. Despite the robustness of this effect, the microscopic model is incomplete and the effect itself is not entirely understood. Here we propose a surface science approachusing scanning tunneling microscopy to study this effect on the atomic scale with single moleculeresolution. The adsorption of polypeptides from solution onto magnetic Au/Co/Au heterostructures allows us to measure quantitatively the spin polarization in helical molecules. Thereby, the flexibilityof α-helix polyalanine molecules is used here to study systematically the transport through molecules and surfaces with adsorbed molecules to determine the influence of the molecular lengths, sequencing, helicity, number of neighbors and coupling towards the current induced molecular spin selectivityand magnetism induced by proximity of adsorbed chiral molecules.