Tunable Rashba spin-orbit coupling and its interplay with multiorbital effect and magnetic ordering at oxide interfaces

Complex oxide heterostructures such as the $\mathrm{LaAl}{\mathrm{O}}_{3}/\mathrm{SrTi}{\mathrm{O}}_{3}$ (LAO/STO) interface are paradigmatic platforms to explore emerging multidegree of freedom coupling and the associated exotic phenomena. In this paper, we reveal the effects of multiorbital and magnetic ordering on Rashba spin-orbit coupling (SOC) at the LAO/STO (001) interface. Based on first-principles calculations, we show that the Rashba spin splitting near the conduction band edge can be tuned substantially by the interfacial insulator-metal transition due to the varied multiorbital effect of the lowest $\mathrm{Ti}\text{\ensuremath{-}}3d\phantom{\rule{4pt}{0ex}}{t}_{2g}$ bands. We further unravel an interplay between Rashba SOC and intrinsic magnetism, in which the Rashba SOC-induced spin polarization is suppressed significantly by the presence of interfacial magnetic ordering. These results deepen our understanding of SOC-related intricate electronic and magnetic reconstruction at the perovskite oxide interfaces and shed light on engineering of oxide heterostructures for all-oxide-based spintronic devices.