THEORY OF SPIN-DEPENDENT TRANSPORT IN HYBRID NANOSTRUCTURES

1.研究了由非磁性金属(N)、铁磁注入器和与N相连的探测器电极组成的器件中的非局域自旋输运，求解了具有任意界面电阻的器件中与自旋有关的输运方程，得到了该器件中有效的自旋注入、积累和自旋输运的最佳条件。我们利用非局域自旋电流注入技术提出了一种非局域自旋操纵。2.我们研究了由两根铁磁线连接在超导体上的器件中的非局域Andreev反射，并阐明了发生交叉Andreev反射的范围。3.我们提出了一种新的超导量子比特，它由一个铁磁结的超导环和一个普通的约瑟夫森结组成。在没有外加磁场的情况下，形成了量子相干二能级。我们利用Haldane-Anderson模型研究了半导体中磁性杂质的电子结构和磁性杂质之间的铁磁相互作用，得到了由于杂质周围扩展的自旋密度的重叠而导致的局域磁矩之间的长程铁磁交换相互作用。5.我们提出了一种估算非磁性金属中杂质的自旋-轨道散射强度的方法。我们证明了由非局域自旋注入技术产生的纯自旋电流产生了可由实验测量的非局域霍尔电压。6.我们建立了描述自旋电流与磁区壁相互作用的微观理论，并提出了新的磁区壁运动方程。我们提出了利用电流驱动的磁区壁运动的纳米结构磁存储器。

1.We studied the nonlocal spin transport in a device consisting of a nonmagnetic metal (N) and ferromagnetic injector and detector electrodes connected to N. We solve the spin-dependent transport equations in a device with arbitrary interface resistance, and obtain the optimal conditions for efficient spin injection, accumulation, and spin transport in the device. We proposed a nonlocal spin manipulation by using the nonlocal spin-current injection technique.2.We studied the nonlocal Andreev reflection in a device consisting of two ferromagnetic wires attached to a superconductor, and clarified the range over which the crossed Andreev reflection takes place.3.We proposed a new superconducting qubit which consists of a superconducting ring with ferromagnetic junctions and an ordinary Josephson junction. A quantum coherent two-level state is formed without an external magnetic field. This feature makes it possible to reduce the size leading to a long decoherence time.4.We studied the electronic structure of a magnetic impurity and the ferromagnetic interaction between magnetic impurities in a semiconductor using the Haldane-Anderson model, and obtain a long-range ferromagnetic exchange interaction between the localized moments due to the overlapping of the extended spin densities around the impurities.5.We proposed a method for estimating the strength of spin-orbit scattering by impurities in non-magnetic metals. We show that the pure spin current created by the nonlocal spin-injection technique produces a nonlocal Hall voltage, which is measurable by experiments.6.We constructed a microscopic theory describing the interaction between spin current and a domain wall, and presented new equations of motion for domain walls. We proposed nano-structured magnetic memories utilizing the current-driven domain wall motion.