非对称与对称$\rm{HgTe/Cd_{x}Hg_{1-x}Te}$双量子阱：无电场的带隙调谐
Asymmetric versus symmetric $\rm{HgTe/Cd_{x}Hg_{1-x}Te}$ double quantum wells: Band gap tuning without electric field
摘要：
研究了沿$[001]$方向生长的双非对称$\rm{HgTe/Cd_{x}Hg_{1-x}Te}$量子阱中的电子态。通过应用于8带Kane $\bf{k}\cdot\bf{p}$模型的包络函数近似计算子带。双量子阱的限制势的不对称性导致间隙开口，这在对称系统中是不存在的，在对称系统中它只能由施加的电场引起。带隙和子带受自旋轨道耦合的影响，这是限制势的不对称性的结果。类电子态和类空穴态主要被限制在不同的量子阱中，它们之间增强的杂化在有限的面内波矢处打开了自旋相关的杂化带隙。我们发现，两个量子阱的宽度的比率和$\rm{Cd_{x}Hg_{1-x}Te}$势垒的摩尔分数控制的类空穴状态和杂化间隙之间的能隙。的能量子带显示出倒序，因此一个非平凡的拓扑相可能出现在系统中。
英文摘要：
We investigate the electron states in double asymmetric $\rm{HgTe/Cd_{x}Hg_{1-x}Te}$ quantum wells grown along the $[001]$ direction. The subbands are computed by means of the envelope function approximation applied to the 8-band Kane $\bf{k}\cdot\bf{p}$ model. The asymmetry of the confining potential of the double quantum wells results in a gap opening which is absent in the symmetric system where it can only be induced by an applied electric field. The band gap and the subbands are affected by spin-orbit coupling which is a consequence of the asymmetry of the confining potential. The electron-like and hole-like states are mainly confined in different quantum wells, and the enhanced hybridization between them opens a spin-dependent hybridization gap at a finite in-plane wavevector. We show that both the ratio of the widths of the two quantum wells and the mole fraction of the $\rm{Cd_{x}Hg_{1-x}Te}$ barrier control both the energy gap between the hole-like states and the hybridization gap. The energy subbands are shown to exhibit inverted ordering, and therefore a nontrivial topological phase could emerge in the system.
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