▎ 摘　　要

The magnetic and transport properties of bowtie-shaped graphene nanoflake (BGNF) are investigated from first principles calculations. The eigen states of ferromagnetic (FM) BGNF near Fermi level are found to be delocalized over the whole flake, whereas those of antiferromagnetic (AFM) BGNF are localized in one side. The different characters result in different transport properties for FM and AFM BGNFs. FM BGNF exhibits perfect spin filtering effect and can serve as a spin filter. Moreover, the conductance of BGNF is much larger in FM state than in AFM state, thus BGNF can serve as a molecular switch. These results suggest that BGNF is a good candidate for future nanoelectronics. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4766914]