Research at the VUV

Highly Anisotropic Dirac Cones in Epitaxial Graphene Modulated by an Island Superlattice

We present a new method to engineer the charge carrier mobility and its directional asymmetry in epitaxial graphene by using metal cluster superlattices self-assembled onto the moire´ pattern formed by graphene on Ir(111).Angle-resolved photoemission spectroscopy reveals threefold symmetry in the band structure associated with strong renormalization of the electron group velocity close to the Dirac point giving rise to highly anisotropic Dirac cones.



Large Band Gap Opening between Graphene Dirac Cones Induced by Na Adsorption onto an Ir Superlattice

We investigate the effects of Na adsorption on the electronic structure of bare and Ir cluster superlattice-covered epitaxial graphene on Ir(111) using angle-resolved photoemission spectroscopy and scanning tunneling microscopy. 

Probing the electronic transmission across a buried metal/metal interface

We monitored the sp-quantum-well states of Ag films on Pt(111) by angle-resolved photoemission in order to examine the electron transmission across the Ag/Pt interface. For thin layers up to 3.5 nm, the Ag states are characterized by broad quasiparticle peaks and a reversal of the parabolic curvature near the center of the surface Brillouin zone. Remarkable departures from the expected nearly-free-electronlike band dispersion persist in films of more than 14 nm thickness.



Influence of the substrate bands on the sp-levels topology of Ag films on Ge(111)

Angle-resolved photoemission spectroscopy and first-principles calculations were employed to analyze unusual features in the electronic structure of ultrathin Ag films grown on Ge(111). The Ag sp-derived quantum well states exhibit hexagonal-like constant energy contours with different in-plane orientations near the center of the surface Brillouin zone, in striking contrast to the expectations for a free-standing Ag(111) layer.


Last Updated on Thursday, 14 May 2020 12:37