Chargeless spin current for switching and coupling of domain walls in magnetic nanowires

• Pure spin current traversing a magnetic quantum wire scatters efficiently from magnetic textures in the wire.
• Pure spin current may transfer spin angular momentum while scattering from domain walls triggering a domain wall dynamics.
• Two nearby domain walls can be coupled controllably via spin current scattering.
• The coupling results in emergent magnetoelectric properties of the formed structures.

We study theoretically the effect of a pure spin current in a quantum wire on magnetic domain walls (DWs). We find that a pure spin current acts on DWs with an effective spin-transfer torque that depends on the mutual DWs separation which results in picosecond magnetization dynamics. Spin-dependent interferences due to spin-current scattering from DWs result in a spin-orbital interaction of the carriers whose strength is determined by the orientations and the spatial separation of DWs. This amounts to an effective dynamical magnetoelectric coupling.