Polarization-dependent spin wave channels in antiferromagnetic magnonic crystals

We theoretically study the spin wave (SW) band structures in antiferromagnetic magnonic crystals formed by applying periodically modulated magnetic fields. We find that when the magnetic field is symmetric, the SW bands with different polarization are degenerate. However, if we consider an asymmetric magnetic field, the degeneracy of the SW bands is lifted due to the breaking of time-reversal symmetry. In this case, we obtain the polarization-dependent SW channels. Furthermore, we show that the tuning of SW band structures both in frequency and momentum spaces can be realized with the help of Dzyaloshinskii–Moriya interaction. The results presented in this work may find their use in antiferromagnet-based magnonic devices.