Spin-Orbit Coupling-Driven Chirality Switching of Spin Waves in Altermagnets

Abstract: Chirality of spin waves offers an advantageous binary carrier for data transmission and processing with ultrafast dynamics and low power consumption. Altermagnets possess intrinsic chirality-splitting spin waves and vanishing net magnetization, thus emerging as ideal platforms to host chirality bits. However, active control of the chiral states remains a key challenge for realizing logic operations in chirality-based circuits. Here, we propose a novel scheme for reversibly switching spin-wave chirality in altermagnets between right- and left-handedness by tuning spin-orbit coupling (SOC) strength. Specifically, for in-plane spin polarization, SOC hybridizes with the altermagnetism, which induces a momentum-dependent competition. The chirality-splitting structure of spin waves is dominated by either SOC or altermagnetism in different Brillouin zone regions, allowing chirality switching by altering their relative strength. An experimental design utilizing an antiferromagnetic substrate to induce SOC and a heavy-metal stripe for chirality detection is proposed. Our work establishes a novel pathway for controlling spin-wave chirality in altermagnets via SOC, laying the groundwork for developing spintronic devices utilizing switchable chiral spin waves as dynamic information carriers.