Electron states emerging at magnetic domain walls of magnetic semiconductors with strong Rashba effect

In the present article, we explore the electron properties of magnetic semiconductors with strong Rashba spin-orbit coupling, taking into account the presence of domain walls at the sample surface. We consider antiphase domain walls separating domains with both in-plane and out-of-plane magnetization as well as noncollinear domain walls. First, we propose the model and unveil the general physical picture of the phenomenon supported by analytical arguments. Further, we perform comprehensive tight-binding numerical calculations to provide a profound understanding of our findings. A domain wall separating domains with any polarization direction is demonstrated to host a bound state. What is more interesting is that we predict that either of these domain walls also induces a one-dimensional resonant state. The surface energy spectrum and spin polarization of the states are highly sensitive to the magnetization orientation in the adjacent domains. The spectral broadening and the spatial localization of the resonant state depend significantly on a relation between the Rashba splitting and the exchange one. Our estimation shows that chiral conducting channels associated with the long-lived resonant states can emerge along the magnetic domain walls and can be accessed experimentally at the surface of BiTeI doped with transition metal atoms.