College of Science, China University of Mining and Technology, Xuzhou, 221116, China.
Nanoscale Res Lett. 2012 Dec 10;7(1):670. doi: 10.1186/1556-276X-7-670.
: Using the nonequilibrium Green's function method, we theoretically study the Andreev reflection(AR) in a four-terminal Aharonov-Bohm interferometer containing a coupled double quantum dot with the Rashba spin-orbit interaction (RSOI) and the coherent indirect coupling via two ferromagnetic leads. When two ferromagnetic electrodes are in the parallel configuration, the spin-up conductance is equal to the spin-down conductance due to the absence of the RSOI. However, for the antiparallel alignment, the spin-polarized AR occurs resulting from the crossed AR (CAR) and the RSOI. The effects of the coherent indirect coupling, RSOI, and magnetic flux on the Andreev-reflected tunneling magnetoresistance are analyzed at length. The spin-related current is calculated, and a distinct swap effect emerges. Furthermore, the pure spin current can be generated due to the CAR when two ferromagnets become two half metals. It is found that the strong RSOI and the large indirect coupling are in favor of the CAR and the production of the strong spin current. The properties of the spin-related current are tunable in terms of the external parameters. Our results offer new ways to manipulate the spin-dependent transport.
我们使用非平衡格林函数方法，理论研究了包含耦合双量子点的四端 Aharonov-Bohm 干涉仪中的安德烈夫反射（AR），该双量子点具有 Rashba 自旋轨道相互作用（RSOI）和通过两个铁磁引线的相干间接耦合。当两个铁磁电极处于平行配置时，由于不存在 RSOI，自旋向上电导等于自旋向下电导。然而，对于反平行排列，由于交叉 AR（CAR）和 RSOI，会发生自旋极化的 AR。我们详细分析了相干间接耦合、RSOI 和磁通量对安德烈夫反射隧穿磁电阻的影响。计算了自旋相关电流，并出现了明显的交换效应。此外，当两个铁磁体变为两个半金属时，由于 CAR，可以产生纯自旋电流。结果表明，强 RSOI 和大的间接耦合有利于 CAR 和强自旋电流的产生。自旋相关电流的性质可以通过外部参数进行调节。我们的结果为操纵自旋相关输运提供了新的途径。
