Giant Rashba-like spin–orbit splitting with distinct spin texture in two-dimensional heterostructures* *Project supported by the Science Fund from the Ministry of Science and Technology of China (Grant Nos. 2017YFA0204904 and 2019YFA0210004), the National Natural Science Foundation of China (Grant Nos. 11674299 and 11634011), the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDB30000000), the Fund of

Abstract

Based on first-principles density functional theory calculation, we discover a novel form of spin-orbit (SO) splitting in two-dimensional (2D) heterostructures composed of a single Bi(111) bilayer stacking with a 2D semiconducting In2Se2 or a 2D ferroelectric α-In2Se3 layer. Such SO splitting has a Rashba-like but distinct spin texture in the valence band around the maximum, where the chirality of the spin texture reverses within the upper spin-split branch, in contrast to the conventional Rashba systems where the upper branch and lower branch have opposite chirality solely in the region below the band crossing point. The ferroelectric nature of α-In2Se3 further enables the tuning of the spin texture upon the reversal of the electric polarization with the application of an external electric field. Detailed analysis based on a tight-binding model reveals that such SO splitting texture results from the interplay of complex orbital characters and substrate interaction. This finding enriches the diversity of SO splitting systems and is also expected to promise for spintronic applications.