Šebesta Jakub, Carva Karel, Kriegner Dominik, Honolka Jan
Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, 121 16 Praha 2, Czech Republic.
Institute of Physics, Academy of Science of the Czech Republic, Na Slovance 2, 182 21 Praha 8, Czech Republic.
Nanomaterials (Basel). 2020 Oct 19;10(10):2059. doi: 10.3390/nano10102059.
Twin domains are naturally present in the topological insulator Bi2Se3 and strongly affect its properties. While studies of their behavior in an otherwise ideal Bi2Se3 structure exist, little is known about their possible interaction with other defects. Extra information is needed, especially for the case of an artificial perturbation of topological insulator states by magnetic doping, which has attracted a lot of attention recently. Employing ab initio calculations based on a layered Green's function formalism, we study the interaction between twin planes in Bi2Se3. We show the influence of various magnetic and nonmagnetic chemical defects on the twin plane formation energy and discuss the related modification of their distribution. Furthermore, we examine the change of the dopants' magnetic properties at sites in the vicinity of a twin plane, and the dopants' preference to occupy such sites. Our results suggest that twin planes repel each other at least over a vertical distance of 3-4 nm. However, in the presence of magnetic Mn or Fe defects, a close twin plane placement is preferred. Furthermore, calculated twin plane formation energies indicate that in this situation their formation becomes suppressed. Finally, we discuss the influence of twin planes on the surface band gap.
双畴自然存在于拓扑绝缘体Bi2Se3中，并强烈影响其性质。虽然已有关于它们在理想Bi2Se3结构中的行为的研究，但对于它们与其他缺陷可能的相互作用却知之甚少。需要更多信息，特别是对于通过磁掺杂对拓扑绝缘体状态进行人工扰动的情况，这一情况最近引起了很多关注。基于分层格林函数形式，利用第一性原理计算，我们研究了Bi2Se3中双平面之间的相互作用。我们展示了各种磁性和非磁性化学缺陷对双平面形成能的影响，并讨论了它们分布的相关变化。此外，我们研究了双平面附近位置处掺杂剂的磁性性质变化以及掺杂剂占据此类位置的偏好。我们的结果表明，双平面至少在3 - 4纳米的垂直距离上相互排斥。然而，在存在磁性Mn或Fe缺陷的情况下，双平面紧密排列是更可取的。此外，计算得到的双平面形成能表明，在这种情况下它们的形成受到抑制。最后，我们讨论了双平面对表面带隙的影响。
