Ferroelectric Rashba semiconductors (FERSC), in which Rashba spin-splitting can be controlled and reversed by an electric field, have recently emerged as a new class of functional materials useful for spintronic applications. The development of concrete devices based on such materials is, however, still hampered by the lack of robust FERSC compounds. Here, we show that the coexistence of large spontaneous polarization and sizeable spin–orbit coupling is not sufficient to have strong Rashba effects and clarify why simple ferroelectric oxide perovskites with transition metal at the B-site are typically not suitable FERSC candidates. By rationalizing how this limitation can be by-passed through band engineering of the electronic structure in layered perovskites, we identify the Bi\({}_{2}\)WO\({}_{6}\) Aurivillius crystal as a robust ferroelectric with large and reversible Rashba spin-splitting, that can even be substantially doped without losing its ferroelectric properties. Importantly, we highlight that a unidirectional spin–orbit field arises in layered Bi\({}_{2}\)WO\({}_{6}\), resulting in a protection against spin-decoherence.

铁电Rashba半导体（FERSC），其中Rashba自旋分裂可以通过电场控制和逆转，最近已经出现，成为可用于自旋电子学应用的新型功能材料。然而，由于缺乏坚固的FERSC化合物，仍阻碍了基于这种材料的混凝土装置的开发。在这里，我们证明了大的自发极化和较大的自旋-轨道耦合并存不足以产生强烈的Rashba效应，并阐明了为什么简单的铁电氧化物钙钛矿与过渡金属在B位置通常不适合作为FERSC候选人。通过合理化如何通过层状钙钛矿中电子结构的能带工程来绕过此限制，我们确定了Bi \（{} _ {2} \） WO\（{} _ {6} \） Aurivillius晶体是一种坚固的铁电体，具有大型且可逆的Rashba自旋分裂，甚至可以在不丧失其铁电特性的情况下进行基本上的掺杂。重要的是，我们强调在层Bi \（{} _ {2} \） WO \（{} _ {6} \）中会出现一个单向自旋轨道场，从而可以防止自旋退相干。