Effect of Torsional Deformation on Spin–Orbit Interaction in Metallic Silicon Nanotubes.

The splitting of spin levels generating minigaps under the action of twisting a non-chiral (7, 7) silicon nanotube around its axis has been studied by the relativistic method of symmetrized linearized augmented cylindrical waves. In the absence of mechanical twisting, the nanotube has inversion symmetry and metallic band structure with spin-degenerate states in the Fermi region. Torsion deformation breaks the inversion symmetry, transforming the nanotube into a chiral system. Due to the joint action of the spin–orbit coupling and the deformation perturbation, the degeneracy of the levels is completely lifted and states with spins up and down are formed. Opposite directions of twisting lead to the reversal of the order of spin levels and can induce oppositely directed spin currents, which is important for the design of elements of nanoelectronics and spintronics. [ABSTRACT FROM AUTHOR]