Topological Phases, Local Magnetic Moments, and Spin Polarization Triggered by C558-Line Defects in Graphene

TL;DR

This paper investigates topological phases, magnetic moments, and spin polarization in graphene with C558-line defects, demonstrating tunable topological transitions and spin filtering effects through strain and Coulomb interactions.

Contribution

It introduces a novel topological defect structure in graphene and explores how strain and Coulomb interactions influence its topological and magnetic properties.

Findings

Topological phase transition can be achieved via strain engineering.

Line defects induce local magnetic moments and ferromagnetic ground states.

Complete spin polarization enables tunable spin filtering in graphene nanoribbons.

Abstract

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.