Formation of topological domain walls and quantum transport properties of zero-line modes in commensurate bilayer graphene systems.

We study theoretically the construction of topological conducting domain walls with a finite width between AB/BA stacking regions via finite element method in bilayer graphene systems with tunable commensurate twisting angles. We find that the smaller is the twisting angle, the more significant the lattice reconstruction would be, so that sharper domain boundaries declare their existence. We subsequently study the quantum transport properties of topological zero-line modes which can exist because of the said domain boundaries via Green's function method and Landauer—Büttiker formalism, and find that in scattering regions with tri-intersectional conducting channels, topological zero-line modes both exhibit robust behavior exemplified as the saturated total transmission G_tot ≈ 2e²/h and obey a specific pseudospin-conserving current partition law among the branch transport channels. The former property is unaffected by Aharonov—Bohm effect due to a weak perpendicular magnetic field, but the latter is not. Results from our genuine bilayer hexagonal system suggest a twisting angle around θ ≈ 0.1° for those properties to be expected, consistent with the existing experimental reports. [ABSTRACT FROM AUTHOR]