Oxide layer dependent orbital torque efficiency in ferromagnet/Cu/oxide heterostructures

The utilization of orbital transport provides a versatile and efficient spin manipulation mechanism. As interest in orbital-mediated spin manipulation grows, we face a new issue to identify the underlying physics that determines the efficiency of orbital torque (OT). In this study, we systematically investigate the variation of OT governed by orbital Rashba-Edelstein effect at the Cu/oxide interface, as we change the oxide material. We find that OT varies by a factor of $\ensuremath{\sim}2$, depending on the oxide. Our results suggest that the active electronic interatomic interaction (hopping) between Cu and the oxygen atom is critical in determining OT. This also gives us an idea of what type of material factors is critical in forming a chiral orbital Rashba texture at the Cu/oxide interface.