Coherent magnon transport in a van der Waals antiferromagnet

Recently developed van der Waals magnets offer a promising platform for advancing spintronics. The weak interlayer antiferromagnetic exchange coupling in van der Waals antiferromagnets allows for unique spin dynamics and control over magnons. In this study, we present the excitation and detection of coherent magnon transport in the van der Waals antiferromagnet CrPS4. We observe pronounced coherent magnon-magnon coupling between the optical and acoustic magnon branches, resulting in hybridized magnon modes that can be tuned by modulating the coupling strength, enabling a tunability across a broad frequency range exceeding 10 GHz. The group velocity of the antiferromagnetic magnons is estimated to be approximately 3.8 km/s. Additionally, we experimentally determine the magnon dispersion in CrPS4 by varying the magnon wavevectors and propose an analytical model for the antiferromagnetic magnon dispersion in CrPS4. Our findings open new avenues for energy-efficient magnonic devices based on van der Waals antiferromagnets.