Configuration-sensitive transport at the domain walls of a magnetic topological insulator

We report on the transport of a two-terminal device containing a domain wall (DW) in a magnetic topological insulator (TI). In the low-energy case, the transport behaviors of the magnetic TI are dominated by chiral edge states (CESs) at the device edges as well as at the DW. We calculate the band structures of magnetic TIs with both a Bloch wall and a Néel wall. For a Bloch wall, two copropagating CESs at the DW are doubly degenerate, while for a Néel wall a split is present. Consequently, the transport is strongly dependent on the DW configuration. In the Bloch wall case, the incoming electron with zero energy is totally reflected regardless of the system parameters. However, in the Néel case, the device functions as a chirality-based Mach-Zehnder interferometry, so that the transmission coefficient oscillates between zero and unity with changes in system parameters. By constructing the scattering matrix of the device from the effective Hamiltonian, these transport behaviors can be well understood.