▎ 摘　　要

The spin-polarized electronic properties for a zigzag-edge graphene nanoribbon (ZGNR) with an extended line defect are investigated, particularly focusing on controlling the effects of an external transverse electric field (E-ext). An ab initio scanning tunneling microscope image for the defective ZGNR is also predicted. Results show that such a ZGNR can exhibit a strong spin polarization and ferromagnetic state, and the spin-filter effect can be significantly tuned and improved by the E-ext. The spin-filter efficiency for our proposed device is predicted to be able to reach up to 60-81% in a large bias range of 0-0.6 V at E-ext = 3.0 V/nm. Mechanisms for such results and the experimental feasibility for the device are suggested. These findings suggest a new possibility for developing nanometer-scale all-carbon spintronic devices. (C) 2013 Elsevier Ltd. All rights reserved.