paper

Violation of the Wiedemann-Franz law in clean graphene layers

arXiv:1406.2940 · doi:10.1103/PhysRevLett.115.056603

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 , where is the momentum relaxation rate, and is the relaxation time of the thermal current due to e-e collisions. Here we study the density and temperature dependence of in the important case of doped, clean single layers of graphene, which exhibit record-high thermal conductivities. We show that at low temperature is 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.

6 pages, 5 appendices (13 pages)

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