Electronic transition of Au-induced atomic chains on Si(5512): A strong similarity with the Au/Si(557) system

We investigated in detail the electronic structures of the Si(5 5 12) surface with Au adsorbates, which features one-dimensional (1D) atomic chains and a 1D metallic band. From angle-resolved UV photoelectron spectroscopy, we resolved that the nearly half-filled 1D band is actually composed of two parallel branches; one is metallic, but the other is insulating with an energy gap of 50 meV below E-F at room temperature. An energy gap evolves gradually from 270 K on the metallic branch, saturating at 75 K with a size of 40 meV below E-F, while the insulating branch is intact. These behaviors are essentially identical with those recently reported on the Au/Si(5 5 7) system [ Phys. Rev. Lett. 91, 196403 (2003) ]. The scanning tunneling microscopy imaging indicates that these surfaces possess common 1D atomic chain structures, while the interchain distance is different. This explains the very similar electronic structure and transition of the two systems.