Magnon spin transport through atomic ferrimagnetic domain walls

It is a well-established notion that the spin of a magnon should be flipped when it passes through a $180^{\circ}$ domain wall (DW) in both ferromagnets and antiferromagnets, while the magnon spin transport through ferrimagnetic DW is still elusive. In this work, we report that the magnon preserves its spin after the transmission through an atomically sharp DW in ferrimagnets, due to the intriguing interband magnon scattering at the domain interface. This finding may provide significant insight to resolve the puzzling insensitivity of magnon spin diffusion to the $180^{\circ}$ ferrimagnetic DWs observed by recent experiments. Our results reveal the unique role of ferrimagnetic DWs in manipulating the magnon spin and may facilitate the design of novel magnonic devices based on ferrimagnets.