Here we show that, in contrast to the observed surface states in well studied pnictogen chalcogenide van der Waals (vdW) topological insulators with quintuple layer (QL) or septuple layer (SL) structure, in superlattices, comprising the alternating QL and SL vdW blocks, the Dirac state becomes accompanied by emergent spin-polarized states of the Rashba type. This specific feature is caused by an inequivalence of the surface and subsurface structural blocks and an electrostatic potential bending near the surface. Within density functional theory and ab initio tight-binding calculations we analyze peculiarities of these states depending on the surface termination, structural parameters, and chemical composition. It is found that their possible hybridization with the Dirac state significantly affects its dispersion and spatial localization. We analyze the influence of intrinsic magnetism on behavior of the termination-dependent surface states for magnetic QL/SL superlattices. These findings provide a better understanding of the existing experimental observations of such QL/SL alternating superlattices.

中文翻译：

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Dirac 和 Rashba 表面状态之间的相互作用，特定于拓扑非平凡范德华超晶格


在这里，我们表明，与在具有五元组层 （QL） 或七层 （SL） 结构的经过充分研究的 pnictogen 硫属化物范德华 （vdW） 拓扑绝缘体中观察到的表面状态相反，在包含交替的 QL 和 SL vdW 块的超晶格中，Dirac 态伴随着 Rashba 型的新兴自旋极化态。这种特定特征是由表面和次表面结构块的不等效以及表面附近的静电势弯曲引起的。在密度泛函理论和从头到来的紧束缚计算中，我们根据表面终端、结构参数和化学成分分析这些状态的特性。研究发现，它们可能与 Dirac 态的杂交显著影响其色散和空间定位。我们分析了本征磁性对磁性 QL/SL 超晶格的终端依赖性表面状态行为的影响。这些发现为更好地理解这种 QL/SL 交替超晶格的现有实验观察提供了更好的理解。