Spin-wave directional coupler based on the Bloch-type magnetic domain walls

Domain walls (DWs) as waveguides of spin waves (SWs) have been used to study SWs propagation properties in ferromagnetic thin films. In this work, we present a spin-wave (SW) directional coupler based on two Bloch-type DWs for the first time with micromagnetic simulations. The distance between the DWs is 40 nm, and the magnetization orientation is is parallel at the central positions of the two magnetic DWs. Under the dipolar interaction, the lowest-width SW mode is split into symmetric and antisymmetric modes, and the SW coupling length L is characterized to be 469nm.