High-Efficiency Switching of the Topological Antiferromagnetic State in Mn3Sn via Magnon Torques

Noncollinear antiferromagnet Mn3Sn offers a large anomalous Hall effect, zero stray field, and terahertz dynamics for high-density ultrafast memory, but switching its topological magnetic state remains challenging. Here, we demonstrate that magnon torques originating from Mn3Sn/NiO/W heterostructures can efficiently switch the octupole moment in Mn3Sn. The inclusion of a NiO interlayer boosts the anomalous Hall signal and lowers the switching current density by one-third, down to 8.45 × 106 A/cm2. Assisted by the spin dynamics simulation, we propose that NiO acts as a spin polarizer, facilitating the reorientation of hard-to-switch magnetic subconfigurations in polycrystalline Mn3Sn. Furthermore, by employing a wedge-shaped NiO layer, field-free deterministic switching has been achieved. Notably, this wedge design also increases the switching ratio of Mn3Sn. Both the switching chirality and the enhanced switching ratio are robust against in-plane external magnetic fields up to 1000 Oe. These findings establish magnon-mediated torque as a promising energy-efficient writing scheme for topological antiferromagnetic memory.