电子输运中自旋轨道耦合和电极非对称磁化引起的非共线磁有序效应

非共线磁有序结构是指体系中所有电子的自旋方向不在一条直线上。非共线磁有序结构的电子输运具有非常独特的物性和应用前景，如自旋场效应晶体管。虽然主要基于第一性原理方法，但不同研究结果之间还存在一定的差异，表明对非共线效应的认识还不足，远远落后于对共线磁有序电子输运的认识。本项目的研究目标是通过电子输运中自旋轨道耦合和左右电极非对称磁化引起的非共线效应的研究，探讨非共线磁有序电子输运的内在特征和物理机制。我们将探讨Bi2Se3表面和纳米带、Fe/Bi2Se3/Fe和Fe/MgO/Fe隧道结的电子输运，揭示自旋轨道耦合、电极非对称磁化、界面电子态、偏压的影响，探索电荷、自旋、界面在电子输运中的独特作用。在方法上，我们将改进第一性原理方法中直接求逆得到格林函数的方法，应用消元法和初等变换法等降低大系统的计算量。本项目的实施对于设计具有优异各向异性磁阻的器件和揭示自旋进动和翻转等重要过程提供新的认识。

Noncollinear magnetic order means the spin orientation of electrons are not aligned along a line. Noncollinear electronic transport is expected to be of intriuging properties and applications, such as spin field effect transistor. Currently, different results based on first principle methods exist, which indicates that the knowledge we have for noncollienar transport is far behind collinear transport. The purpose of our proposal is to investigate the noncollinear effect of transport by considering spin-orbit coupling and asymmetrically magnetized leads and to show the underlying physical mechanisms. On the one hand, we will study electronic transport of pure Bi2Se3 surface and nanoribbon, Fe/Bi2Se3/Fe and Fe/MgO/Fe magnetic tunnel junctions, in order to show the effect of spin-orbit coupling, asymmetrically magnetized leads, interface states, bias voltage and intrinsic relationship of charge, spin and interface. On the other hand, developing a method to reduce large computational demand is very important for noncollinear electronic transport. We will apply elimination method and recursive method to obtain the Green''s function, instead of inversing the Hamiltonian equation directly. Our proposal will provide considerable insights into the design of magnetic devices of excellent anisotropic magnetoresistance and the discovery of important processes, e.g. spin flip and spin precession.