Realizing polarization-dependent unidirectional magnon channel in antiferromagnetic domain wall

Abstract

Achieving unidirectional spin wave (or magnon) transport in domain wall (DW) represents the key step for designing functional magnonic devices. Here, we theoretically investigate the propagation behavior of spin waves (SWs) in antiferromagnetic DW when the Dzyaloshinskii–Moriya interaction (DMI) and/or spin transfer torque (STT) are considered. On the one hand, we find that the DMI lifts the degeneracy of magnon bands, from which one can obtain pure right- or left-handed polarized SWs. On the other hand, the nonreciprocal attenuation of magnons induced by STT is identified. Interestingly, we realize the polarization-dependent unidirectional propagation of SWs when the nonadiabatic coefficient β exceeds a critical value. Moreover, the micromagnetic simulations verify the theoretical predictions with good agreement. Our work provides a simple method for achieving unidirectional magnons with desired polarity in antiferromagnetic DW, which is indispensable for future magnonic computing and communication.