论文标题
在有缺陷的BI $ _2 $ SE $ _3 $中，非线性混合表面缺陷状态
Non-linear hybrid surface-defect states in defective Bi$_2$Se$_3$
论文作者
论文摘要
假定拓扑绝缘子的表面状态对晶体中的非磁性缺陷是可靠的。但是，最近的理论模型和实验表明，即使是非磁性缺陷也会扰动这些状态。我们的第一原理计算表明，BI $ _2 $ SE $ _3 $中的SE空缺的存在比仅仅是该结构的N掺杂效果更大，这只会将Fermi级别转移到Dirac Point上。我们观察到在费米水平附近固定的非线性频带的出现，而狄拉克锥则更深地转移到价带。我们将这些特征归因于频段结构中的表面和缺陷状态之间的相互作用，并根据SE空位相对于表面的位置和对称性之间的杂交本身之间的杂交。我们的结果使我们更加了解了从BI $ _2 $ SE $ _3 $中的缺陷中出现的异国情调物理学，而这些物理学在先前的研究中仍未得到探索。
Surface-states of topological insulators are assumed to be robust against non-magnetic defects in the crystal. However, recent theoretical models and experiments indicate that even non-magnetic defects can perturb these states. Our first-principles calculations demonstrate that the presence of Se vacancies in Bi$_2$Se$_3$, has a greater impact than a mere n-doping of the structure, which would just shift the Fermi level relative to the Dirac point. We observe the emergence of a non-linear band pinned near the Fermi level, while the Dirac cone shifts deeper into the valence band. We attribute these features in the bandstructure to the interaction between the surface and defect states, with the resulting hybridization between these states itself depending on the position and symmetry of the Se vacancy relative to the surfaces. Our results bring us a step closer to understanding the exotic physics emerging from defects in Bi$_2$Se$_3$ that remained unexplored in prior studies.
