Spin Transport Properties of Carbon Nanotubes by Ferromagnetic Zigzag Triangular Defects: A First-Principles Study

Carrying out first-principles density functional theory combined with a non-equilibrium Green's function approach, we study the electronic structure and transport properties of triangle zigzag hole (ZTH) incorporated single-walled carbon nanotubes (CNTs). The magnetism in CNTs is induced by the development of quasibound defect states of pi-orbitals at the zigzag edges of ZTH. We find interesting transport properties of defective (10,10) CNT exhibiting resonant peaks and broad transmission dips. The electronic transmission is completely suppressed for particular spin-orientation corresponding to those broad dips. These peaks and dips of transmission show robust nature upon the increasing size of ZTHs. Importantly, we show a remarkable control over the tuning of completely spin-polarized transmission at energy-scale by applying a reasonable external electric field. Spinpolarization of transmission also switches at Fermi energy by reversing the direction of the transverse electric field with an intensity of +/- 0.2 V angstrom(-1) . This carbon magnetism in CNTs together with switchable spin filtering through external field turns those into promising candidates for electric circuits and spintronic devices.