Handed Magnon Propagation in Easy-Axis Antiferromagnetic α-Fe₂O₃.

Abstract

Antiferromagnetic magnons with intrinsic handedness provide a unique degree of freedom enabling spin-selective control, as left-handed (LH) and right-handed (RH) magnons carry opposite spin angular momenta. While previous studies have mainly focused on antiferromagnetic resonance modes, the coherent transport of nondegenerate handed magnons has remained unexplored in antiferromagnets. In this work, the excitation and detection of LH and RH propagating magnons in the easy-axis antiferromagnet α-Fe₂O₃ is demonstrated. Below the Morin transition temperature (T_M), an external magnetic field along the easy axis lifts the degeneracy between two modes without altering their group velocities, establishing field-insensitive transport as a distinct characteristic of antiferromagnetic magnons. In addition, the Dzyaloshinskii-Moriya interaction and magnetic anisotropy strongly modulate the frequency and group velocity, as well as the amplitude and damping of LH and RH magnons, particularly near T_M. These results identify internal magnetic interactions as key factors controlling handed magnon propagation. The findings advance the fundamental understanding of handed magnon dynamics and open new pathways for spin-resolved, energy-efficient, and ultrafast magnonic devices.