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[PAST EVENT] CONDENSED MATTER SEMINAR
November 11, 2014
2pm
Abstract:
The Wiedemann-Franz law, connecting the electronic thermal conductivity to the electrical conductivity of a disordered metal, is generally found to be well satisfied even when electron-electron (e-e) interactions are strong. In ultra-clean conductors, however, large deviations from the standard form of the law are expected, due to the fact that e-e interactions affect the two conductivities in radically different ways. Thus, the standard Wiedemann-Franz ratio between the thermal and the electric conductivity is reduced by a factor 1 + ? /? ee, where 1/? is the momentum relaxation rate, and 1/? ee/th is the
relaxation time of the thermal current due to e-e collisions. Here we study the density and tempera- ture dependence of 1/? ee in the important case of doped, clean single layers of graphene, which exhibit record-high thermal conductivities. We show that at low temperature 1/? ee is 8/5 of the quasiparticle decay rate. We also show that the many-body renormalization of the thermal Drude weight coincides with that of the Fermi velocity.
The Wiedemann-Franz law, connecting the electronic thermal conductivity to the electrical conductivity of a disordered metal, is generally found to be well satisfied even when electron-electron (e-e) interactions are strong. In ultra-clean conductors, however, large deviations from the standard form of the law are expected, due to the fact that e-e interactions affect the two conductivities in radically different ways. Thus, the standard Wiedemann-Franz ratio between the thermal and the electric conductivity is reduced by a factor 1 + ? /? ee, where 1/? is the momentum relaxation rate, and 1/? ee/th is the
relaxation time of the thermal current due to e-e collisions. Here we study the density and tempera- ture dependence of 1/? ee in the important case of doped, clean single layers of graphene, which exhibit record-high thermal conductivities. We show that at low temperature 1/? ee is 8/5 of the quasiparticle decay rate. We also show that the many-body renormalization of the thermal Drude weight coincides with that of the Fermi velocity.