Angle-resolved photoemission study of the surface and bulk electronic structure of Mg(0001) and Mg(112-bar0).

摘要: Angle-resolved ultraviolet photoemission spectroscopy measurements have been made from the (0001) and (112\ifmmode\bar\else\textasciimacron\fi{}0) surfaces of magnesium in photon energy range 15 to 115 eV. Both bulk surface features are identified. The occupied bands along [0001] direction characterized by measured eigenvalues at \ensuremath{\Gamma} point: ${\ensuremath{\Gamma}}_{1}^{+}$=6.15\ifmmode\pm\else\textpm\fi{}0.1 eV, ${\ensuremath{\Gamma}}_{3}^{+}$=1.7\ifmmode\pm\else\textpm\fi{}0.1 ${\ensuremath{\Gamma}}_{4}^{\mathrm{\ensuremath{-}}}$=0.9\ifmmode\pm\else\textpm\fi{}0.1 bandwidth, as for both surfaces, is 10% smaller than that predicted band-structure calculations, while ${\ensuremath{\Gamma}}_{3}^{+}$-${\ensuremath{\Gamma}}_{4}^{\mathrm{\ensuremath{-}}}$ band gap twice big calculated. narrower experimental bandwidth related fact excitation spectrum system measured, origin wider not clear. final states higher 28 eV above ${E}_{F}$ well described a free-electron effective mass ${m}^{\mathrm{*}}$/m=1.04, originating 6.15 below Fermi level, low-energy deviate greatly free-electron-like behavior. peak widths [112\ifmmode\bar\else\textasciimacron\fi{}0] significantly larger interacting electron-gas theory. increase near middle band, due final-state effects. binding \ensuremath{\Gamma}\ifmmode\bar\else\textasciimacron\fi{} state on has redetermined be 1.6\ifmmode\pm\else\textpm\fi{}0.1 A M\ifmmode\bar\else\textasciimacron\fi{} 1.1\ifmmode\pm\else\textpm\fi{}0.1 shows sharp intensity resonance \ensuremath{\Elzxh}\ensuremath{\omega}=44 giving location ${\ensuremath{\Gamma}}_{4}^{\mathrm{\ensuremath{-}}}$ symmetry state. similar \ensuremath{\Elzxh}\ensuremath{\omega}=26 surface-state dispersions \ensuremath{\Gamma}\ifmmode\bar\else\textasciimacron\fi{}-M\ifmmode\bar\else\textasciimacron\fi{} direction.