First-principles investigation of transport properties through longitudinal unzipped carbon nanotubes

We report a first-principles investigation of transport through longitudinal unzipped carbon nanotube based devices. The graphene nanoribbons can be obtained experimentally by unzipping carbon nanotubes in the longitudinal direction. The basic component of our devices is partially unzipped carbon nanotube that consists of graphene nanoribbons and carbon nanotubes as leads. When the edges of graphene are saturated by hydrogen atoms, the system has finite magnetic moment and hence the transport is spin polarized. Our results show that as the Fermi energy is varied the system can change from an insulator to a spin-down half metal, an insulator again, and finally a spin-up half metal. Hence a spin-filter device can be designed from this kind of systems.