Rashba splitting in polar-nonpolar sandwich heterostructure: a DFT study

In this study, we employ density functional theory based first-principles calculations to investigate the spin-orbit effects in the electronic structure of a polar-nonpolar sandwich heterostructure namely LaAlO 3 / SrTiO 3 / LaAlO 3 . Our focus on the Ti-3d bands reveals an inverted ordering of the SrTiO 3 - t 2 g orbital near the n-type interface, which is consistent with earlier experimental work. In contrast, toward the p-type interface, the orbital ordering aligns with the natural ordering of SrTiO 3 orbitals, influenced by crystal field splitting. In the presence of SOC, a notable inter-orbital coupling between t 2 g and e g orbitals is observed within the tetragonal slab, a phenomenon not reported before in the SrTiO 3 -based 2D systems. Additionally, our observations highlight that the cubic Rashba splitting in this system surpasses the linear Rashba splitting, contrary to experimental findings. This comprehensive analysis contributes to a refined understanding of the role of orbital mixing in Rashba splitting in the sandwich oxide heterostructures.