Wang Mei-Juan, Wang Jun, Liu Jun-Feng
Department of Physics, Southeast University, Nanjing, 210096, China.
Department of Physics, School of Physics and Electronic Engineering, Guangzhou University, Guangzhou, 510006, China.
Sci Rep. 2019 Mar 4;9(1):3378. doi: 10.1038/s41598-019-39002-x.
We report a theoretical study of the quantized spin pump in a traditional quantum pump device that is based on the helical edge states of a quantum spin Hall insulator. By introducing two time-dependent magnetizations out of phase as the pumping parameters, we found that when the Fermi energy resides in the energy gap opened by magnetization, an integer number of charges or spins can be pumped out in a pumping cycle and ascribed to the possible topological interface state born in between the two pumping potentials. The quantized pump current can be fully spin-polarized, spin-unpolarized, or pure spin current while its direction can be abruptly reversed by some system parameters such as the pumping phase and local gate voltage. Our findings may shed light on generation of a quantized spin pump.
我们报道了对一种基于量子自旋霍尔绝缘体螺旋边缘态的传统量子泵浦器件中量子化自旋泵浦的理论研究。通过引入两个相位不同的随时间变化的磁化强度作为泵浦参数，我们发现当费米能级位于由磁化强度打开的能隙中时，在一个泵浦周期内可以泵出整数个电荷或自旋，这归因于两个泵浦势之间可能产生的拓扑界面态。量子化的泵浦电流可以是完全自旋极化的、自旋非极化的或纯自旋电流，而其方向可以通过一些系统参数（如泵浦相位和局部栅极电压）突然反转。我们的发现可能为量子化自旋泵浦的产生提供启示。
