| By using fully-relativistic first-principles calculations, we study edge states of the Bi(001) nanoribbon on Bi substrate. Freestanding bismuth zigzag nanoribbons (ZBNRs) which was considered to be a topological insulator in a past study are found to have two spin degenerate bands around the Fermi energies, whose wave functions are localized at the edges. The wave functions are sharply localized at the edges at the zone boundary and become delocalized as the wave number decreases. In the case of the ZBNR on Bi substrates, the inversion symmetry is broken. As a result, the spin degenerate bands split and thus the densities of the states near the Fermi level have broad distributions; thus the electronic structures are expected to be stabilized. Because of the edge state near the Fermi energy, the conduction along the edge lines is expected. |
|