Topological Domain Walls in Graphene Nanoribbons with Carrier Doping

Abstract

We theoretically study magnetic ground states of doped zigzag graphene nanoribbons and the emergence of topological domain walls. Using the Hartree-Fock mean-field approach and an effective continuum model, we demonstrated that the carrier doping stabilizes a magnetic structure with alternating antiferromagnetic domains, where the doped carriers are accommodated in topological bound states localized at the domain wall. The energy spectrum exhibits a Hofstadter-like fractal spectral evolution as a function of the carrier density, where minigaps are characterized by the Chern number associated with the adiabatic charge pump in moving domain walls. A systematic analysis for nanoribbons with different widths revealed that the ferromagnetic domain-wall phase emerges in relatively wide ribbons, while the colinear domain-wall phase arises in narrower ribbons.