▎ 摘　　要

Magneto-electronics properties of fluorine-passivated Christmas Tree graphene nanoribbons (F-CTGNRs) are investigated theoretically. It is found that F-CTGNRs have a ferromagnetic ground state and can be a spin metal, a spin semiconductor, a spin half-metal, or a spin gapless semiconductor, completely depending on their geometrical sizes. More importantly, for the F-CTGNR based device, the dual spin-filtering effect with the perfect (100%) spin polarization and high-performance dual spin diode effect with a rectification ratio about 10(10) can be achieved. It means that the F-CTGNR can act as an excellent dual spin diode. The magnetoresistance (MR) value larger than 10(4)% can be reached in the calculated bias region, which is comparable to the previously reported experimental values for the MgO tunnel junction. These distinctive features can be attributed to their unique band overlap pattern for two electrodes and particular sensitivity to a switching magnetic field. Our findings suggest that F-CTGNRs have desirable natures for developing magnetic devices. (C) 2014 Elsevier B.V. All rights reserved.