Seminar on Disorder and strong electron correlation: "Graphene with vacancies: Density of states, transport, multifractality"
Starts 17 Jan 2013 11:30
Ends 17 Jan 2013 20:00
Central European Time
Leonardo da Vinci Building Luigi Stasi Seminar Room
Strada Costiera, 11
I - 34151 Trieste (Italy)
A single vacancy in an otherwise clean flake of graphene introduces a topological defect. It punches a new state at zero energy into the Dirac cone (zero mode). A finite concentration of such vacancies produces a narrow impurity band that determines the low energy/frequency response of the flake. A peculiarity of this band is that its properties are very sensitive to details of the impurity placings:
All impurities in one sublattice imply a density of states (DoS) vanishing in the zero energy limit, while impurities distributed equally over both sublattices (compensated) exhibit a diverging DoS.
We present a numerical study focussing mainly on the DoS at very low energies. We resolve the Dyson-singularity with compensated disorder and investigate the amplitude statistics (multifractality) of the associated wavefunctions. Finally, we present transport calculations addressing the possibility of Anderson-localization on percolation clusters preempting the classical localization transition.