  A systematic study of the electronic properties of single layer Sb
(antimonene) nanoribbons is presented. By using a 6-orbital tight-binding
Hamiltonian, we study the electronic band structure of finite ribbons with
zigzag or armchair termination. We show that there is good agreement between ab
initio calculations and the tight-binding model. We study how the size of the
gap can be controlled by applying an external bias potential. An electric field
applied perpendicular to the antimonene layer is found to increase the band
gap, while a transverse bias potential leads to a position dependent reduction
of the band gap. Both kinds of bias potential break inversion symmetry of the
crystal. This, together with the strong intrinsic spin-orbit coupling of
antimonene, leads to spin-splitting of the valence band states.
