Events

R. G. Herb Condensed Matter Seminars

<< Fall 2015 Spring 2016 Summer 2016 >>
Subscribe your calendar or receive email announcements of events

Events During the Week of January 17th through January 24th, 2016

Monday, January 18th, 2016

No events scheduled

Tuesday, January 19th, 2016

No events scheduled

Wednesday, January 20th, 2016

No events scheduled

Thursday, January 21st, 2016

Transport coefficients of graphene: Interplay of impurity scattering, Coulomb interaction, and optical phonons
Time: 10:00 am
Place: 5310 Chamberlin Hall
Speaker: Hong-Yi Xie, Department of Physics and Astronomy, Rice University
Abstract: We study the electric and thermal transport of the Dirac carriers 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 effects of quenched disorder, Coulomb interactions, and electron--optical-phonon scattering. Via an unbiased numerical solution to the Boltzmann equation we calculate the electrical conductivity, thermopower, and electronic component of the thermal conductivity, and discuss the validity of Mott's formula and of the Wiedemann-Franz law. An analytical solution for the disorder-only case shows that screened Coulomb impurity scattering, although elastic, violates the Wiedemann-Franz law even at low temperature. For the combination of carrier-carrier Coulomb and short-ranged impurity scattering, we observe the crossover from the interaction-limited (hydrodynamic) regime to the disorder-limited (Fermi-liquid) regime. In the former, the thermopower and the thermal conductivity follow the results anticipated by the relativistic hydrodynamic theory. On the other hand, we find that optical phonons become nonnegligible at relatively low temperatures and that 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.
Host: Alex Levchenko
Add this event to your calendar

Friday, January 22nd, 2016

No events scheduled