Shi Likun, Lou Wenkai, Cheng F, Zou Y L, Yang Wen, Chang Kai
SKLSM, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083, China.
Beijing Computational Science Research Center, Beijing 100094, China.
Sci Rep. 2015 Oct 16;5:15266. doi: 10.1038/srep15266.
Based on the Born-Oppemheimer approximation, we divide the total electron Hamiltonian in a spin-orbit coupled system into the slow orbital motion and the fast interband transition processes. We find that the fast motion induces a gauge field on the slow orbital motion, perpendicular to the electron momentum, inducing a topological phase. From this general designing principle, we present a theory for generating artificial gauge field and topological phase in a conventional two-dimensional electron gas embedded in parabolically graded GaAs/InxGa1-xAs/GaAs quantum wells with antidot lattices. By tuning the etching depth and period of the antidot lattices, the band folding caused by the antidot potential leads to the formation of minibands and band inversions between neighboring subbands. The intersubband spin-orbit interaction opens considerably large nontrivial minigaps and leads to many pairs of helical edge states in these gaps.
基于玻恩-奥本海默近似,我们将自旋轨道耦合系统中的总电子哈密顿量分为缓慢的轨道运动和快速的带间跃迁过程。我们发现,快速运动会在缓慢的轨道运动上诱导出一个与电子动量垂直的规范场,从而诱导出一个拓扑相。基于这一通用设计原理,我们提出了一种理论,用于在嵌入具有反点晶格的抛物型渐变GaAs/InxGa1-xAs/GaAs量子阱中的传统二维电子气中产生人工规范场和拓扑相。通过调整反点晶格的蚀刻深度和周期,反点势引起的能带折叠导致了微带的形成以及相邻子带之间的能带反转。子带间的自旋轨道相互作用打开了相当大的非平凡微隙,并在这些微隙中导致了许多对螺旋边缘态的出现。