Electronic structure of atomic chains on vicinal Si(111)-Au

Abstract

Unusual electronic states are found for gold-induced chain and ladder structures on vicinal Si(111) surfaces, such as $\mathrm{Si}(111)5\ifmmode\times\else\texttimes\fi{}2\ensuremath{-}\mathrm{Au}$ and Si(557)-Au. As two-dimensional reference the $\mathrm{Si}(111)\sqrt{3}\ifmmode\times\else\texttimes\fi{}\sqrt{3}\ensuremath{-}\mathrm{Au}$ surface is investigated. The highly stepped Si(557)-Au surface is metallic, despite an even electron count. That is explained by two half-filled, nearly degenerate bands. On the $\mathrm{Si}(111)5\ifmmode\times\else\texttimes\fi{}2\ensuremath{-}\mathrm{Au}$ surface we find a band that changes continuously from one dimensional at its maximum to two dimensional at its minimum. It exhibits a pseudogap within 0.3 eV of the Fermi level ${E}_{F},$ where the spectral weight is strongly reduced. $\mathrm{Si}(111)\sqrt{3}\ifmmode\times\else\texttimes\fi{}\sqrt{3}\ensuremath{-}\mathrm{Au}$ exhibits an electron pocket at $\ensuremath{\Gamma}$ that changes its filling continuously with increasing Au coverage.