Urgent: Announcing seminar this morning

[Cond.Matt. & Stat.Mech.Section]

SEMINAR on   Disorder and strong electron correlations


 

Thursday, 17 January -  11:30 a.m.


 

Luigi Stasi Seminar Room,  Leonardo Building - first floor

 


Ferdinand EVERS    (KIT, Karlsruhe)

 


"Graphene with vacancies:    Density of states, transport, multifractality"

 
 
Abstract

 
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.