Spin-polarized current generated by carbon chain and finite nanotube

Inspired by recent progress of experimental fabrication of carbon structure [Borrnert et al., Phys. Rev. B 81, 085439 (2010)], we proposed a scheme to generate spin-polarized current based on an all-carbon system consisting of carbon nanotube and chain. The transmission spectra are calculated based on density functional theory combined with nonequilibrium Green's function method. It is found that the spin-polarized current can be achieved in the proposed system by partial contact between nanotube and chain, without using the dopants, ferromagnetic electrodes, and external electric field. Moreover, our results show that the device containing carbon nanotubes with large length and diameter can produce the current with 100% spin polarization, which is essential for spintronic devices. Physical mechanisms and the comparison with the results of graphene are also discussed. (C) 2010 American Institute of Physics. [doi:10.1063/1.3510537]