Van der Waals heterostructures formed by stacking different types of 2D materials are attracting increasing attention due to new emergent physical properties such as interlayer excitons. Recently synthesized atomically thin indium selenide (InSe) and antimony (Sb) individually exhibit interesting electronic properties such as high electron mobility in the former and high hole mobility in the latter. In this work, we present a first-principles investigation on the stability and electronic properties of ultrathin bilayer heterostructures composed of InSe and Sb single layers. The calculated electronic band structures reveal a direct band gap semiconducting nature of the InSe/Sb heterostructures independent of stacking pattern. Taking spin-orbit coupling into account, we find a large Rashba spin splitting at the bottom of conduction band, which originates from the atomic spin-orbit coupling with the symmetry breaking in the heterostructure. The strength of the Rashba spin splitting can be tuned by applying in-plane biaxial strain or an out-of-plane external electric field. The presence of large Rashba spin splitting together with a suitable band gap in InSe/Sb bilayer heterostructures make them promising candidates for spin field-effect transistor and optoelectronic device applications.

中文翻译：

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InSe和Sb单层范德华异质结构中的直接带隙和强Rashba效应

由于层间激子等新出现的物理特性，通过堆叠不同类型的二维材料形成的范德华异质结构越来越受到关注。最近合成的原子级薄硒化铟 (InSe) 和锑 (Sb) 分别表现出有趣的电子特性，例如前者的高电子迁移率和后者的高空穴迁移率。在这项工作中，我们对由 InSe 和 Sb 单层组成的超薄双层异质结构的稳定性和电子特性进行了第一性原理研究。计算出的电子能带结构揭示了 InSe/Sb 异质结构的直接带隙半导体性质，与堆叠模式无关。考虑到自旋轨道耦合，我们发现在导带底部有一个大的 Rashba 自旋分裂，这源于原子自旋轨道耦合与异质结构中的对称性破坏。Rashba 自旋分裂的强度可以通过应用面内双轴应变或面外外部电场来调整。InSe/Sb 双层异质结构中大 Rashba 自旋分裂的存在以及合适的带隙使它们成为自旋场效应晶体管和光电器件应用的有希望的候选者。