Electronic and Magnetic Engineering in Zigzag Graphene Nanoribbons Having a Topological Line Defect at Different Positions with or without Strain

Abstract

Using first-principles calculations, we perform a comprehensive study of the locations of a topological line defect (a line defect consisting of alternating pairs of pentagons and octagons or 585 LD) on the electronic and magnetic properties of zigzag graphene nanoribbon, with 12 zigzag chains (12-ZGNR) with or without tensile strain (e). When e = 0, it is found that 585 LD preferably forms near the edge. As 585 LD shifts from the center to the edge, the systems experience transitions from antiferromagnetic (AFM) semiconductors to an AFM half-metal and then to a ferromagnetic (FM) metal. As e increases, the band gaps of the AFM semiconductors decrease and then the AFM semiconductors change into AFM half-metals. Finally, all the AFM systems turn into FM metals. The critical e values of these transitions decrease as 585 LD moves to the edge. A similar behavior can also be found in 8- and 16-ZGNRs. However, the AFM half-metal region disappears in 8- and 16-ZGNRs due to different variation tendencies of the c...