  We study the electronic properties of a novel topological defect structure
for graphene interspersed with C558-line defects along the Armchair boundary.
This system has the topological property of being topologically three-periodic
and the type-II Dirac-fermionic character of the embedded topological phase. At
the same time, we show computationally that the topological properties of the
system are overly dependent on the coupling of this line defect. Using strain
engineering to regulate the magnitude of hopping at the defect, the position of
the energy level can be easily changed to achieve a topological phase
transition. We also discuss the local magnetic moment and the ferromagnetic
ground state in the context of line defects, which is the conclusion after
considering additional Coulomb interactions. This leads to spin polarization of
the whole system. Finally, by modulating the local magnetic moment at the
position of the line defect, we achieve a tunable spin quantum conductance in a
one-dimensional nanoribbon. Near the Fermi energy level, it also has the
property of complete spin polarization. Consequently, spin filtering can be
achieved by varying the incident energy of the electrons.
