Efficient field-free magnetization switching through orbital-current-enhanced magnon torque
In the authors' words
Efficient control of magnetization is essential for the development of spintronics devices. Various mechanisms, including spin currents, orbital currents, and magnon currents, have been explored to achieve magnetization switching. Among them, magnon currents facilitate low-dissipation transport of spin angular momentum, potentially mitigating energy dissipation associated with Ohmic loss. So far, the magnon currents excited by spin currents have been well-established, while the role of orbital currents in magnon excitation remains much less explored. Here, we report efficient magnon torques in a RuO2/NiO/ferromagnet system, where spin and orbital currents generated by RuO2 jointly excite magnon currents in NiO. Notably, the magnon currents exhibit both in-plane and out-of-plane polarizations, manifesting a high in-plane spin Hall conductivity σs,y = 143.8 × 103 ℏ /2e Ω−1 m−1 and out-of-plane spin Hall conductivity σs,z = 8.3 × 103 ℏ /2e Ω−1 m−1, which enables field-free switching of perpendicular magnetization with low-power consumption. Our findings reveal that spin and orbital currents in RuO2 can jointly excite magnon currents in NiO, enabling efficient field-free switching of perpendicular magnetization and paving the way to low-power spintronic devices. Orbital currents have been shown to allow for efficient switching of magnetization. Here, Shi et al. build on this point, demonstrating how spin and orbital currents in RuO2 can jointly excite magnons in an adjacent magnetic insulator, NiO, leading to enhanced magnon torque efficiency and field-free magnetization switching.
Appeared: Friday, September 25. Nature Communications. Peer-reviewed journal.