Spin wave filter and spin wave accelerator/decelator based on a narrow ferrimagnetic domain wall

We present a theoretical study of scattering of spin waves by a domain wall with width of a few lattice spacing in a ferrimagnetic (FiM) spin chain. We find that a narrow FiM domain wall exhibit a different behavior in comparison with its ferromagnetic and antiferromagnetic counterparts: at the center of the domain wall, the direction of spin at the sublattice with smaller spin is perfectly oriented normal to the easy axis. This particular form of a FiM domain wall leads to a strong dependence of spin waves scattering pattern on the state of polarization of a spin wave, suggesting utilization of a FiM narrow domain wall as a spin wave filter. Moreover, we find that in the case of an abruptly sharp FiM domain wall, the wave vector of the spin wave increases after passing through the domain wall leading to a change in the group velocity of the spin wave, indicating acceleration/deceleration of the spin wave. Thus, a sharp FiM domain wall, depending on the wave vector of the incoming wave, could serve as a spin wave accelerator/decelerator in spintronics devices.