Nonreciprocal spin waves in ferrimagnetic domain-wall channels

Abstract

We theoretically investigate the propagation of spin waves confined in a N\'eel-type ferrimagnetic domain-wall channel in the presence of the interfacial Dzyaloshinskii-Moriya interaction (DMI). We observe a nonreciprocal spin-wave propagation induced by the antisymmetric chiral DMI, which can be manipulated by changing the net angular momentum or the polarity of domain walls. Considering that the band gap of spin waves excited in domain walls is significantly reduced, the three-magnon processes are applied to nonlinearly detect this bounded mode in the narrow channel, which enables us to quantify the frequency and the wave vector by analyzing the spectrum of the transmitted spin wave outside the domain wall and to determine the DMI strength. These findings are useful for fabricating energy-efficient magnetic devices and measuring the interfacial DMI in ultra narrow ferrimagnetic stripes.