Bulk and surface electronic structures of the semimetal Bi studied by angle-resolved photoemission spectroscopy

An angle-resolved photoemission study of the Bi (111) single crystal has been carried out in order to investigate in detail the bulk and surface electronic structures. The valence-band photoemission spectra of the Bi (111) single crystal exhibit the features derived from the Bi $6p$-derived bulk valence band, the surface state in the spin-orbit gap, and the surface resonance state. From the detailed angle-resolved photoemission spectra, the dispersion relations of the bulk valence band of Bi were determined along the $T\ensuremath{-}U$ high-symmetry line in the bulk Brillouin zone. These experimental band dispersions are compared with the theoretical results of the band calculations, obtained by a pseudopotential method and a recent third-neighbor tight-binding method. The dispersion relation of the surface state in the spin-orbit gap and surface resonance state on the Bi (111) clean surface were also determined experimentally along the $\overline{\ensuremath{\Gamma}}\ensuremath{-}\overline{M}$ symmetry line in the surface Brillouin zone.