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

在手性分子体系中，电流诱导的自旋选择性过程引起了人们的极大兴趣，因为电子沿着手性主干结构的传播即使在环境条件下也会导致明显的自旋极化。尽管这种效应具有很强的稳健性，但微观模型是不完整的，而且这种效应本身也没有完全被理解。在这里，我们提出了一种表面科学的方法，利用扫描隧道显微镜在原子尺度上用单分子溶液来研究这一效应。多肽在磁性Au/Co/Au异质结上的吸附使我们能够定量测量螺旋分子中的自旋极化。因此，本文利用α-螺旋聚丙氨酸分子的柔韧性，系统地研究了分子和吸附分子表面的输运行为，以确定分子长度、序列、螺旋度、邻位数和耦合对电流诱导的分子自旋选择性的影响，以及由吸附的手性分子的邻近性引起的磁性。

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.