2009 APS March Meeting
Volume 54, Number 1
Monday–Friday, March 16–20, 2009;
Pittsburgh, Pennsylvania
Session H1: Electronic Structure of Disordered Graphene
8:00 AM–11:00 AM,
Tuesday, March 17, 2009
Room: Spirit of Pittsburgh Ballroom A
Sponsoring
Unit:
DCMP
Chair: Allan MacDonald, University of Texas at Austin
Abstract ID: BAPS.2009.MAR.H1.4
Abstract: H1.00004 : Ground-state Properties of Inhomogeneous Graphene Sheets*
9:48 AM–10:24 AM
Preview Abstract
Abstract
Author:
Marco Polini
(NEST-CNR-INFM and Scuola Normale Superiore di Pisa )
When inter-valley scattering is weak and gauge fields due to {\it
e.g.} ripples are neglected, doped and gated graphene sheets can
be described using an envelope-function Hamiltonian with a new
sublattice pseudospin degree-of freedom, an ultrarelativistic
massless-Dirac free-fermion term, a pseudospin {\it scalar}
disorder potential, and a non-relativistic instantaneous
Coulombic interaction term. There is considerable evidence from
experiment that this simplified description of a honeycomb
lattice of Carbon atoms is usually a valid starting point for
theories of those observables that depend solely on the
electronic properties of $\pi$-electrons near the graphene Dirac
point [1]. Although the use of this model simplifies
the physics considerably it still leaves us with a many-body
problem without translational invariance, which we do not know
how to solve.
In this talk we present a Kohn-Sham-Dirac
density-functional-theory (DFT) scheme for graphene sheets that
treats slowly-varying inhomogeneous scalar external potentials
and electron-electron interactions on an equal
footing [2]. The theory is able to account for
the unusual property that the exchange-correlation contribution
to chemical potential increases with carrier density in
graphene [3,4]. Consequences of this property, and
advantages and disadvantages of using the DFT approach to
describe it, are discussed. The approach is illustrated by
solving the Kohn-Sham-Dirac equations self-consistently for a
model random potential describing charged point-like impurities
located close to the graphene plane. The influence of
electron-electron interactions on these non-linear screening
calculations is discussed at length, in the light of recent
experiments [5,6] reporting evidence for the
presence of electron-hole puddles in nearly-neutral graphene sheets.
\\[4pt]
[1]
A.K. Geim and K.S. Novoselov, Nature Mater. {\bf 6}, 183 (2007);
A.K. Geim and A.H. MacDonald, Phys. Today {\bf 60}, 35 (2007);
A.H. Castro Neto, F. Guinea, N.M.R. Peres, K.S. Novoselov, and
A.K. Geim, arXiv:0709.1163v2 (2007).\\[0pt]
[2]
M. Polini, A. Tomadin, R. Asgari, and A.H. MacDonald, Phys. Rev.
B {\bf 78}, 115426 (2008).\\[0pt]
[3]
Y. Barlas, T. Pereg-Barnea, M. Polini, R. Asgari, and A.H.
MacDonald, Phys. Rev. Lett. {\bf 98}, 236601 (2007); M. Polini,
R. Asgari, Y. Barlas, T. Pereg-Barnea, and A.H. MacDonald, Solid
State Commun. {\bf 143}, 58 (2007). \\[0pt]
[4]
E.H. Hwang, B.Y.-K. Hu, and S. Das Sarma, Phys. Rev. Lett. {\bf
99}, 226801 (2007).\\[0pt]
[5]
J. Martin, N. Akerman, G. Ulbricht, T. Lohmann, J.H. Smet, K. von
Klitzing, and A. Yacoby, Nature Phys. {\bf 4}, 144 (2008).\\[0pt]
[6]
V.W. Brar, Y. Zhang, C. Girit, F. Wang, A. Zettl, and M. Crommie,
Bull. Am. Phys. Soc. {\bf 53} (2), 443 (2008).
*Work done in collaboration with Andrea Tomadin, Reza Asgari, and A.H. MacDonald. M.P. was supported by the CNR-INFM ``Seed Projects".
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2009.MAR.H1.4