Recently, it has been known that the hidden Rashba (R-2) effect in two-dimensional materials gives rise to a physical phenomenon called spin-layer locking (SLL). However, not only its underlying fundamental mechanism has been unclear, but also there are only a few materials exhibiting weak SLL. Here, through the first-principles density functional theory and model Hamiltonian calculation, we reveal that the R-2 SLL can be determined by the competition between the sublayer–sublayer interaction and the spin–orbit coupling, which is related to the Rashba strength. In addition, the orbital angular momentum distribution is another crucial point to realize the strong R-2 SLL. We propose that a 2D material Si₂Bi₂ possesses an ideal condition for the strong R-2 SLL, whose Rashba strength is evaluated to be 2.16 eVÅ, which is the greatest value ever observed in 2D R-2 materials to the best of our knowledge. Furthermore, we reveal that the interlayer interaction in a bilayer structure ensures R-2 states spatially farther apart, implying a potential application in spintronics.

最近，已知二维材料中隐藏的Rashba（R-2）效应会引起一种称为自旋层锁定（SLL）的物理现象。但是，不仅其基本的机理尚不清楚，而且仅有少数几种材料的SLL较弱。在这里，通过第一原理密度泛函理论和模型哈密顿量计算，我们发现R-2 SLL可以由子层-子层相互作用和自旋-轨道耦合之间的竞争来确定，这与Rashba强度有关。此外，轨道角动量分布是实现强R-2 SLL的另一个关键点。我们建议使用2D材料Si ₂ Bi ₂拥有强大的R-2 SLL理想条件，其Rashba强度评估为2.16eVÅ，据我们所知，这是2D R-2材料中观察到的最大值。此外，我们揭示了双层结构中的层间相互作用可确保R-2状态在空间上相距较远，这意味着在自旋电子学中有潜在的应用。