The electronic structure of bismuth(111).

다국어 초록 (Multilingual Abstract)

The (111) surface of the semimetal bismuth has been studied using angle-resolved photoemission spectroscopy. Five two-dimensional (2D) bands have been observed within 1 eV binding energy which originate in the topmost bilayer at the surface. Three of these bands can be found within 150 meV binding energy. They show sixfold rotational symmetry and have surface state character while the remaining two bands show threefold rotational symmetry and have surface resonance character. The 2D Fermi surface is highly anisotropic occupying a small fraction of the surface Brillouin zone (SBZ). A line shape analysis of the band generating the 2D hole Fermi surface along <overline>Γ</overline> M reveals an electron-phonon coupling constant of λ = 0.6. The hexagonal shape of the electron pocket in the center of the SBZ along with a temperature dependent gap opening at the Fermi level suggests the formation of a surface charge density wave with a transition temperature of about <italic>T_CDW</italic> = 75 K. The bulk band structure along FT has been measured and the final state band structure has been determined for an energy range where the free electron approximation breaks down. Spectra of the 5d core levels exhibit a component which is split off in energy by ≈200 meV. The energy as well as the spectral width and relative intensity of the split off structure are strongly modulated by the final state electron momentum <italic>k</italic>_⊥ and <italic> k</italic>_∥, resembling the periodicity of the surface and bulk Brillouin zone. A model is proposed relating the double peak structure to energy losses from discrete interband transitions as a result of scattering events in the photoemission process.