Enhancement of magnon transport length in easy-plane antiferromagnets

Long-distance magnon transport in antiferromagnets is crucial for developing future magnon-based devices with high speed, density, and stability. However, the magnon decay length remains limited in easy-plane antiferromagnets due to the mismatch between injected magnon modes and eigen magnon modes, as well as the resulting dephasing process. Here, we improved the magnon decay length in easy-plane antiferromagnetic α-Fe2O3 (0001) single crystal by utilizing coherent magnons as carriers. The polarization and phase of coherent magnons maintain the single state during transport, effectively eliminating the dephasing effect. At room temperature, coherent magnons exhibit a magnon decay length of 3 μm, substantially longer than the 320 nm observed for incoherent magnons. Notably, the incoherent magnon transport displays temperature independence approaching the Morin temperature, highlighting the fundamental limitations of incoherent magnons. Our findings demonstrate the advantages of coherent magnons and suggest a promising pathway for long-distance magnon transport in easy-plane antiferromagnets.