电场和磁场作用下带反转结中稳健的中间带隙态
Robust midgap states in band-inverted junctions under electric and magnetic fields
摘要：
由重原子制成的几种IV-VI族半导体化合物，例如Pb $_{1-x}$ Sn $_{x}$ Te，可以在它们的化学组成变化时在布里渊区的$L$点处经历带反转。这种反转产生拓扑上不同的相位，其特征在于拓扑不变量的变化。在$\mathbf{k}\cdot\mathbf{p}$理论的框架中，带反转可以被看作是基本带隙的符号的改变。一个两个带模型内的带函数近似预测的外观midgap界面状态与狄拉克锥色散带反转的结，即，当间隙沿生长方向改变符号。我们提出了一个深入的研究这些界面电子态的存在下，交叉的电场和磁场，电场被施加沿带反转结的生长方向。我们表明，狄拉克锥是强大的，并持续存在，即使领域是强大的。此外，我们还指出半导体能带中电子态的朗道能级可以被电场剪裁。因此，利用本文研究的特性，可调谐器件可能是可实现的。
英文摘要：
Several IV-VI semiconductor compounds made of heavy atoms, such as Pb$_{1-x}$Sn$_{x}$Te, may undergo band-inversion at the $L$ point of the Brillouin zone upon variation of their chemical composition. This inversion gives rise to topologically distinct phases, characterized by a change in a topological invariant. In the framework of the $\mathbf{k}\cdot\mathbf{p}$ theory, band-inversion can be viewed as a change of sign of the fundamental gap. A two-band model within the envelope-function approximation predicts the appearance of midgap interface states with Dirac cone dispersions in band-inverted junctions, namely, when the gap changes sign along the growth direction. We present a thorough study of these interface electron states in the presence of crossed electric and magnetic fields, the electric field being applied along the growth direction of a band-inverted junction. We show that the Dirac cone is robust and persists even if the fields are strong. In addition, we point out that Landau levels of electron states lying in the semiconductor bands can be tailored by the electric field. Tunable devices are thus likely to be realizable exploiting the properties studied herein.
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