Orbital torque and efficient magnetization switching using ultrathin Co|Al light-metal interfaces: Experiments and modeling.

The emergence of the orbital degree of freedom in modern orbitronics offers a promising alternative to heavy metals for the efficient control of magnetization. In this context, identifying interfaces that exhibit orbital–momentum locking and an orbital Rashba–Edelstein response to an external electric field is of primary importance. In this work, we experimentally investigate the Co|Al system and extend the study to Co|Pt|Al structures. We show that inserting ultrathin Pt layers between Co and Al can significantly modify the orbital properties, highlighting the critical role of Co|Al orbital bonding in generating orbital polarization. We further model the orbital response of these systems using semi-phenomenological approaches and linear-response theory within the framework of density-functional theory.