Role of edge dehydrogenation in magnetization and spin transport of zigzag graphene nanoribbons with line defects

We investigate the effects of edge dehydrogenation on magnetism and spin transport of zigzag graphene nanoribbons (ZGNRs) with line defects (558defect and 57defect) by the first-principles calculations. Results show that magnetization can be induced or strengthened obviously in 558defect-ZGNRs unterminated by hydrogen, but not for 57defect-ZGNRs. This is because a spin-polarized a edge state appears near the Fermi level and strengthens spin-splitting of energy bands at bare edges of the 558defect-ZGNRs. Moreover, compared with pristine ZGNRs, the 558defect-ZGNRs with bare edges can realize a transition from antiferromagnetic coupling to ferromagnetic coupling between both edges. In addition, the spin-filter efficiency can be effectively improved in our proposed devices by edge dehydrogenation. Our results demonstrate that the presence of sigma edge state near the Fermi level plays an important role in controlling spin transport of the graphene-based spintronic devices. (C) 2015 Elsevier B.V. All rights reserved.