Magnon spin transport around the compensation magnetic field in easy-plane antiferromagnetic insulators

In this work, we theoretically study the magnon spin transport in easy-plane antiferromagnetic insulators in the presence of an in-plane magnetic field. By exactly calculating the magnon spectrum, we find that the band splitting due to magnetic anisotropy can be fully compensated by the external field at a particular strength, which makes the dynamics nearly equivalent to an easy-axis antiferromagnet. As a result, the intrinsic magnon spin Hall effect due to the dipole-dipole interaction, previously predicted in easy-axis antiferromagnets, is activated in easy-plane antiferromagnets. The compensation feature also allows the field control of magnon spin lifetime and hence the spin diffusion length. The compensation feature is robust against biaxial anisotropy. Published under an exclusive license by AIP Publishing.