Research at the VUV

Energy-momentum mapping of d-derived Au(111) states in a thin film

The quantum well states of a film can be used to sample the electronic structure of the parent bulk material and determine its band parameters. We highlight the benefits of two-dimensional film band mapping, with respect to complex bulk analysis, in an angle-resolved photoemission spectroscopy study of the 5d states of Au(111). Discrete 5d-derived quantum well states of various orbital characters form in Au(111) films and span the width of the corresponding bulk bands



Evidence for a diamondlike electronic band structure of Si multilayers on Ag(111)

Silicon multilayers on Ag(111) have been suggested to exhibit the structure of silicene, a material that has been heralded as a novel basis for microelectronic applications. However, our angle-resolved photoemission spectra (ARPES) from silicon multilayers on Ag(111) and of the silver-induced reconstruction of Si(111) demonstrate, from the close match in the valence level band structures, that the films exhibit a sp3 diamondlike structure. 



Spin-orbit interaction and Dirac cones in d-orbital noble metal surface states

Here, we report a joint photoemission and ab initio study of spin-orbit effects in the deep d-orbital surface states of a 24-layer Au film grown on Ag(111) and a 24-layer Ag film grown on Au(111), singling out a conical intersection (Dirac cone) between two surface states in a large surface-projected gap at the time-reversal symmetric M bar points. Unlike the often isotropic dispersion at Γ bar point Dirac cones, the M bar point cones are strongly anisotropic. 



Silicene on Ag(111): A honeycomb lattice without Dirac bands

By means of angle-resolved photoemission spectroscopy and density-functional theory calculations we show that the π-symmetry states lose their local character and the Dirac cone fades out. The formation of an interface state of free-electron-like Ag origin is found to account for spectral features that were theoretically and experimentally attributed to silicene bands of π character.



Last Updated on Thursday, 14 May 2020 12:37