Tuning spin polarization and spin transport of zigzag graphene nanoribbons by line defects

From first-principles methods, the spin-dependent electronic properties of zigzag-edged graphene nanoribbons (ZGNRs) with a line defect (558-defect) are investigated systematically and compared to those of the pristine ZGNR. Results show that the line defect possesses an obvious tuning effect on the spin-polarization of the edge carbon atoms of the defective ZGNRs, and the spin-polarization and spin-transport are sensitive to the position of line defects. The defective ZGNRs can realize a transition from antiferromagnetism (AFM) to ferrimagnetism and ferromagnetism (FM) via changing the position of line defects from the center to the zigzag edge of ZGNRs. More importantly, when the line defect is located at the one edge, the defective ZGNRs exhibit the long-range magnetic ordering at edges with a high Curie temperature up to 276 K, and the defective ZGNR system can generate a high-performance spin-filter effect in the large bias range, 0.0-0.5 V. Such a sensitive modulation for the spin-polarization and spin-transport holds great promise for applications of the graphene-based systems in nano-scale spintronic devices.