Orbital exchange-mediated current control of magnetism.

Abstract

Electrical control of magnetism is critical for advancing both fundamental understanding and technological applications of magnetic systems. Although gate-voltage-induced carrier modulation enables tuning of magnetic properties, current-induced mechanisms offer more dynamic and versatile control. To date, such control has been investigated exclusively through spin exchange interactions between itinerant and localized electrons, leaving the role of orbital exchange interactions entirely unexplored. Here, we establish a theoretical framework for current-induced control of magnetism mediated by orbital exchange interactions, incorporating the full orbital degrees of freedom, including orbital angular momentum and orbital angular position. We show that nonequilibrium orbital densities generated by the orbital Hall and orbital Edelstein effects induce not only damping-like and field-like torques, but also current-driven modifications of the magnetic anisotropy, damping, and gyromagnetic ratio. Our estimates suggest that orbital-exchange-mediated effects can exceed their spin-exchange counterparts, positioning orbital exchange as a dominant mechanism for magnetism control. We further propose experimental schemes based on harmonic Hall and spin-torque ferromagnetic resonance measurements to quantify these effects. These findings uncover a previously unrecognized route for electrical control of magnetism and extend current-induced effects to a broader class of materials beyond conventional dipolar magnets.