Zhang Lin, Tong Peiqing
Department of Physics and Institute of Theoretical Physics, Nanjing Normal University, Nanjing 210023, People's Republic of China. Department of Applied Physics, College of Science, Nanjing Forestry University, Nanjing 210037, People's Republic of China.
J Phys Condens Matter. 2017 Dec 13;29(49):495303. doi: 10.1088/1361-648X/aa97b8.
We propose a possible electrical controllable spin pump based on a zigzag silicene nanoribbon ferromagnetic junction by applying two time-dependent perpendicular electric fields. By using the Keldysh Green's function method, we derive the analytic expression of the spin-resolved current at the adiabatic approximation and demonstrate that two asymmetric spin up and spin down currents can be pumped out in the device without an external bias. The pumped currents mainly come from the interplay between the photon-assisted spin pump effect and the electrically-modulated energy band structure of the tunneling junction. The spin valve phenomena are not only related to the energy gap opened by two perpendicular staggered potentials, but also dependent on the system parameters such as the pumping frequency, the pumping phase difference, the spin-orbit coupling and the Fermi level, which can be tuned by the electrical methods. The proposed device can also be used to produce a pure spin current and a 100% polarized spin current through the photon-assisted pumping process. Our investigations may provide an electrical manipulation of spin-polarized electrons in graphene-like pumping devices.
我们提出了一种基于锯齿形硅烯纳米带铁磁结的可能的电可控自旋泵，通过施加两个随时间变化的垂直电场来实现。利用凯尔迪什格林函数方法，我们推导出了绝热近似下自旋分辨电流的解析表达式，并证明在没有外部偏压的情况下，该器件可以泵出两个不对称的自旋向上和自旋向下电流。泵浦电流主要来自光子辅助自旋泵效应与隧穿结电调制能带结构之间的相互作用。自旋阀现象不仅与两个垂直交错势打开的能隙有关，还取决于诸如泵浦频率、泵浦相位差、自旋轨道耦合和费米能级等系统参数，这些参数可以通过电学方法进行调节。所提出的器件还可以通过光子辅助泵浦过程用于产生纯自旋电流和100%极化的自旋电流。我们的研究可能为类石墨烯泵浦器件中的自旋极化电子提供电操控方法。
