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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
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SEQUENCE:0
UID:UW-Physics-Event-3907
DTSTART:20160121T160000Z
DURATION:PT1H0M0S
DTSTAMP:20260426T062958Z
LAST-MODIFIED:20160104T135640Z
LOCATION:5310 Chamberlin Hall
SUMMARY:Transport coefficients of graphene: Interplay of impurity scat
 tering\, Coulomb interaction\, and optical phonons\, R. G. Herb Conden
 sed Matter Seminar\, Hong-Yi Xie\, Department of Physics and Astronomy
 \, Rice University
DESCRIPTION:We study the electric and thermal transport of the Dirac c
 arriers in  monolayer graphene using the Boltzmann-equation approach. 
 Motivated by  a recent thermopower measurement [F. Ghahari\, H.-Y. Xie
 \, M.S. Foster\,  and P. Kim\, in preparation]\, we consider the effec
 ts of quenched  disorder\, Coulomb interactions\, and electron--optica
 l-phonon  scattering. Via an unbiased numerical solution to the Boltzm
 ann  equation we calculate the electrical conductivity\, thermopower\,
  and  electronic component of the thermal conductivity\, and discuss t
 he  validity of Mott's formula and of the Wiedemann-Franz law. An  ana
 lytical solution for the disorder-only case shows that screened  Coulo
 mb impurity scattering\, although elastic\, violates the  Wiedemann-Fr
 anz law even at low temperature. For the combination of  carrier-carri
 er Coulomb and short-ranged impurity scattering\, we  observe the cros
 sover from the interaction-limited (hydrodynamic)  regime to the disor
 der-limited (Fermi-liquid) regime. In the former\,  the thermopower an
 d the thermal conductivity follow the results  anticipated by the rela
 tivistic hydrodynamic theory. On the other  hand\, we find that optica
 l phonons become nonnegligible at relatively  low temperatures and tha
 t the induced electron thermopower violates  Mott's formula. Combining
  all of these scattering mechanisms\, we  obtain the thermopower that 
 quantitatively coincides with the  experimental data.
URL:https://www.physics.wisc.edu/events/?id=3907
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