Nonlocal magnon transport in a magnetic domain wall waveguide

Magnetic domain walls (DWs) function as a waveguide for low-energy magnons. In this paper we develop the theory for the nonlocal transport of these bound magnons through a ferromagnetic insulator (FMI) that are injected and detected electrically in adjacent normal metal leads by spin-flip scatting processes and the (inverse) spin-Hall effect. Our setup requires a twofold degeneracy of the magnetic ground state, which we realize by an easy axis and hard axis anisotropy, in the FMI. This is readily provided by a broad range of materials. The DW is a topologically protected feature of the system and we obtain the nonlocal spin transport through it, and thereby we provide a framework for reconfigureable magnonic devices.