Magnon-Mediated Orbital Torque Switching through an Antiferromagnetic Insulator.

Magnon-mediated spin-orbit torque (SOT) has emerged as a promising mechanism for efficient magnetization control in spintronic devices. Here, we provide experimental evidence for magnon-mediated orbital torque─the orbital analogue of magnon-mediated SOT. We demonstrate that the current-induced torque in Ti/NiO/CoPt heterostructures is governed by the orbital Hall effect in the Ti layer and exhibits a strong dependence on the antiferromagnetic ordering of NiO, indicating the magnon-mediated transport of orbital angular momentum through the antiferromagnetic insulator. Notably, the magnon-mediated orbital torque enables efficient manipulation of perpendicular magnetization with reduced electrical currents. These results open a pathway toward highly efficient orbitronic devices driven by magnons.