Theoretical Investigation of Spin-Dependent Transport from Adsorbates to Magnetic Substrates

金属表面有机分子的自组装单分子膜(SAM)为未来的分子电子学提供了有趣的性质。在TU München的P.Feulner团队最近的实验中，这个想法已经扩展到磁性铁、钴和镍上的分子自旋电子学。在这个项目中，我们建议使用第一性原理、电子结构和量子动力学方法来研究这类过程。为此，我们建议从两个方面着手：一方面，需要研究自组装膜的形成、稳定性和结构。采用半局域交换相关泛函的自旋极化密度泛函计算为描述元素金属中巡回电子的磁性提供了一个强有力的框架。对于曲面的处理，我们将把它们与周期边界条件超网格几何方法相结合。另一方面，我们将用各种实时含时密度泛函理论和含时CI计算方法，用团簇方法研究通过吸附到磁性衬底上的自旋相关电荷的输运。最近似的量子动力学方法可以处理10,000个电子的数量级，这使我们相信可以使团簇足够大，以便在相应的时间尺度上收敛。我们将特别注意影响电荷转移时间标度差异的各种机制，例如自旋相关的势垒高度或态密度。

Self-assembled monolayers (SAMs) of organic molecules on metal surfaces offer intriguing properties for future molecular electronics. In recent experiments by the group of P. Feulner at the TU München this idea has been extended to molecular spintronics on magnetic iron, cobalt, and nickel. We propose in this project to investigate these kinds of processes using first principles electronic structure and quantum dynamical methods. To do so, we propose to proceed in two directions: On the one hand, the formation, stability, and structure of SAMs need to to be investigated. Spin-polarized DFT calculations with semi-local exchange-correlation functionals provide a powerful framework to describe the magnetism of itinerant electrons in elemental metals. For the treatment of surfaces we will combine them with periodic boundary condition supercell geometry approaches. On the other hand, we will study the spin-dependent charge transport through the adsorbates to a magnetic substrate with a variety of real-time time-dependent DFT and time-dependent CI calculations, using a cluster approach. The most approximate quantum dynamical approach can treat of the order of 10,000 electrons, which makes us confident that the clusters can be made large enough for convergence on the relevant time-scale. Special attention will be given to various mechanisms that influence the difference of the time-scales of the charge transfer, such as spin-dependent barrier heights or density of states.