Signatures of spin-orbit interaction in transport properties of finite carbon nanotubes in a parallel magnetic field

The transport properties of finite nanotubes placed in a magnetic field parallel to their axes are investigated. Upon including spin-orbit coupling and curvature effects, two main phenomena are analyzed which crucially depend on the tube's chirality: i) Finite carbon nanotubes in a parallel magnetic field may present a suppression of current due to the localization at the edges of otherwise conducting states. This phenomenon occurs due to the magnetic-field dependent open boundary conditions obeyed by the carbon nanotube's wave functions. The transport is fully suppressed above threshold values of the magnetic field which depend on the nanotube chirality, length and on the spin-orbit coupling. ii) Reversible spin polarized currents can be obtained upon tuning the magnetic field, exploiting the curvature-induced spin-orbit splitting.