Electronic Band Structure and Magnetic Properties of Naked Zigzag Graphene Nano Ribbons Lying Symmetrically

Abstract

We have studied the electronic band structures and magnetic properties of the naked zigzaggraphene nano ribbons lying symmetrically on the ribbon’s middle under an external tensilestrain along the edge direction by using first principle calculations. We have found that theground state of unstrained line defects zigzag graphene nanoribbon’s was antiferromagnetismin which the magnetic moment localized on the line defect was negligible. When an externaltensile strain was applied along the edge direction, the energy band near the Fermi level isspin-split. The band splitting was enhanced with increasing the strain, leading to an increaseof the local magnetic moments on the defect. Graphene nanoribbons with zigzag edges arecharacterized with special localized states, showing a ferromagnetic order in the same edgebut antiferromagnetic order between two opposite edges. The ferromagenetic ordering hasbeen found to exist in graphene materials with defect such as vacancies, topological defects,edges and hydrogen chemisorptions. When the defect position changes a transmission froman antiferromagnetism semiconductor to an antiferro magnetism half metal appears. Thetensile strain along the zigzag direction of graphene with topological line defects. Theantiferromagnetic coupling between the magnetic moments on the edges and the line defectsleaded to a turnover of polarization direction on one edge of a critical value of the tensilestrain, causing the line defect zigzag graphene nanoribbon to be ferromagnetic. The obtainedresults were found in good agreement with previous results.