Anatomy of torques from orbital Rashba textures: The case of Co/Al interfaces

In the context of orbitronics, the rise of the orbital angular momentum generated at light metal interfaces from orbital textures via orbital Rashba-Edelstein effects now represent extraordinary alternatives to the usual heavymetal spin-based materials. In the wake of very recent experimental results [S. Krishnia et al., Nano Lett. 23, 6785 (2023)], starting from state-of-the-art density functional theory simulations, we provide theoretical insights into the emergence of very strong orbital torques at the Co/Al interface featuring a strong orbital Rashba texture. By using linear response theory, we calculate the exerted orbital torque amplitudes, mainly of intraband field-like character, acting on the ultrathin Co. Moreover, we show that inserting a single atomic plane of Pt between Co and Al is enough to suppress the effect, raising questions about the anatomy of the torque action clearly behaving differently than in the standard way. This work opens routes to the engineering of spintronic devices.