2009 APS March Meeting
Volume 54, Number 1
Monday–Friday, March 16–20, 2009;
Pittsburgh, Pennsylvania
Session J1: Ballistic-Diffusive Crossover in Graphene Electron Transport
11:15 AM–2:15 PM,
Tuesday, March 17, 2009
Room: Spirit of Pittsburgh Ballroom A
Sponsoring
Unit:
DCMP
Chair: Sankar Das Sarma, University of Maryland
Abstract ID: BAPS.2009.MAR.J1.2
Abstract: J1.00002 : A self-consistent theory for graphene transport.*
11:51 AM–12:27 PM
Preview Abstract
Abstract
Author:
Shaffique Adam
(University of Maryland)
Arguably, one of the most intriguing properties of graphene
transport is the
non-vanishing ``minimum conductivity'' at the Dirac point. The
carrier
density in these single monatomic sheets of carbon can be
continuously tuned
from electron-like carriers for large positive gate bias to
hole-like
carriers for negative bias. The physics close to zero carrier
density (also
called the intrinsic or Dirac region), is now understood to be
dominated by
the inhomogeneous situation where the local potential fluctuates
around
zero, breaking the landscape into puddles of electrons and holes.
Here, we
propose and discuss a particular hierarchy of approximations to
understand
graphene transport properties that includes a tight binding
approximation
for the low energy effective Hamiltonian,
Random-Phase-Approximation to
treat electron-electron interactions, the semi-classical
Boltzmann transport
theory to treat scattering of electrons by short and long-ranged
disorder,
and a self-consistent Fermi-Thomas approximation to treat
impurity induced
density inhomogeneity [1-2]. We find that this self-consistent
theory for
graphene transport is in remarkable agreement with recent
experiments [3-5].
To better understand the range of validity of this theory we
relax some of
the assumptions and include the effects percolation [6];
calculate transport
properties using an effective medium theory [7]; and examine the
effects of
phase-coherent quantum transport [8]. We believe that while most
of the dc
transport experiments on bulk graphene samples at zero magnetic
field are in
the parameter regime correctly captured by the semi-classical
diffusive
self-consistent transport theory, we demonstrate theoretically
that by
tuning external parameters, it is possible to access several
other transport
regimes.\\[4pt]
References:\\[0pt]
[1] Adam, Hwang, Galitski and Das Sarma, Proc. Nat. Acad. Sci. USA
\textbf{104}, 18392 (2007);
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[2] Hwang, Adam, and Das Sarma, PRL \textbf{98}, 186806 (2007);
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[3] Tan et al. PRL\textbf{ 99}, 246803 (2007);
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[4] Chen et al. Nature Physics \textbf{4}, 377 (2008);
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[5] Jang et al. PRL \textbf{101},146805 (2008);
\\[0pt]
[6] Adam et al. PRL \textbf{101}, 046404 (2008);
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[7] Rossi, Adam, and Das Sarma, arXiv:0809.1425v1 (2008);
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[8] Adam, Brouwer, and Das Sarma, arXiv:0811.0609v1 (2008).
*This work is supported by US-ONR and NRI-SWAN and done in collaboration with Sankar Das Sarma, Michael Fuhrer, Euyheon Hwang, Victor Galitski, Piet Brouwer, and Enrico Rossi.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2009.MAR.J1.2