Electronic structure of graphene hybrid systems: impurities and interactions
Event details
| Date | 08.11.2013 |
| Hour | 14:15 |
| Speaker | Tim Wehlin, Institute of Theoretical Physics, Bremen Center for Computational Materials Science, University of Bremen |
| Location | |
| Category | Conferences - Seminars |
Graphene combines ultimate two-dimensionality with a special electronic structure: it is a Dirac material, which allows for strong doping and offers unprecedented opportunities for chemical functionalization. Here, we show how “Diracness” determines the interaction of graphene with adatoms, molecules, and its response to electric fields.
First, resonant scatterers such as hydrogen adatoms can strongly enhance the low-energy density of states in graphene. We study the impact of these impurities on transport and electronic screening and find a two-faced behavior: Kubo formula calculations reveal an increased dielectric function ε upon the creation of midgap states but no metallic divergence at small momentum transfer q→0. A new length scale beyond which screening is suppressed emerges, which we identify with the Anderson localization length.
At increasing coverage interactions between the impurities emerge. We investigate how the interplay of deformation energies and electronically mediated interactions affect the way impurities arrange. We show that charge doping can trigger transitions between several adsorbate phases.
Finally, the problem of Coulomb interactions in layered materials is addressed. Free standing graphene is shown to feature simultaneously strong local and non-local Coulomb interaction terms. We demonstrate that the non-local Coulomb interactions are decisive for stabilizing the Dirac electron sea in graphene against instabilities towards strongly correlated phases.
First, resonant scatterers such as hydrogen adatoms can strongly enhance the low-energy density of states in graphene. We study the impact of these impurities on transport and electronic screening and find a two-faced behavior: Kubo formula calculations reveal an increased dielectric function ε upon the creation of midgap states but no metallic divergence at small momentum transfer q→0. A new length scale beyond which screening is suppressed emerges, which we identify with the Anderson localization length.
At increasing coverage interactions between the impurities emerge. We investigate how the interplay of deformation energies and electronically mediated interactions affect the way impurities arrange. We show that charge doping can trigger transitions between several adsorbate phases.
Finally, the problem of Coulomb interactions in layered materials is addressed. Free standing graphene is shown to feature simultaneously strong local and non-local Coulomb interaction terms. We demonstrate that the non-local Coulomb interactions are decisive for stabilizing the Dirac electron sea in graphene against instabilities towards strongly correlated phases.
Practical information
- Informed public
- Free
Organizer
- ICMP (Arnaud Magrez and Raphaël Butté)
Contact
- Arnaud Magrez