Graphene with Rashba spin-orbit interaction and coupling to a magnetic layer: Electron states localized at the domain wall

TL;DR

This paper theoretically investigates electron states at magnetic domain walls in graphene with Rashba spin-orbit coupling, revealing localized edge modes, their properties, and the system's quantum anomalous Hall phase.

Contribution

It demonstrates the emergence of multiple localized edge modes at domain walls in graphene with Rashba spin-orbit interaction and magnetic coupling, linking topological invariants to edge state count.

Findings

Two one-dimensional edge bands per Dirac point are found.

The system exhibits a quantum anomalous Hall phase with four localized modes.

Wavefunction decay involves real and imaginary components.

Abstract

Electron states localized at a magnetic domain wall in a graphene caplayer with Rashba spin-orbit interaction and coupled to a magnetic overlayer are studied theoretically. It is shown that two one-dimensional bands of edge modes propagating along the domain wall emerge in the energy gap for each Dirac point, and the modes associated with different Dirac points K and K' are the same. The coefficients describing decay of the corresponding wavefunctions with distance from the domain wall contain generally real and imaginary terms. Numerical results on the local spin density and on the total spin expected in the edge states characterized by the wavenumber $k_y$ are presented and discussed. The Chern number for a single magnetic domain on graphene indicates that the system is in the quantum anomalous Hall phase, with two chiral modes at the edges. In turn, the number of modes localized at the domain wall is determined by the difference in Chern numbers on both sides of the wall. These numbers are equal to 2 and -2, respectively, so there are four modes localized at the domain wall.