Wiedemann-Franz law in graphene

Abstract

We analyze a well-known experimental work [J. Crossno et al., Science 351, 1058 (2016)] which reported on the failure of the Wiedemann-Franz law in graphene at $T\sim 10$-$100\mathrm{K}$, attributing this failure to the non-Fermi liquid nature of the Dirac fluid associated with undoped intrinsic graphene. In spite of serious theoretical efforts, the reported observations remain unexplained. Our detailed quantitative analysis based on Fermi liquid considerations, which apply to extrinsic doped graphene, establishes that one possible explanation for the reported observations is the opening of a gap at the Dirac point, induced perhaps by the boron nitride substrate. We suggest that more experiments are necessary to resolve the issue, and we believe that the experiment may not actually have anything to do with Dirac fluid hydrodynamics, but relates to finite-temperature low-density bipolar diffusive transport by electrons and holes in the presence of short- and long-range disorder, and phonons.

13 pages, 9 figures

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• Driving Viscous Hydrodynamics in Bulk Electron Flow in Graphene Using Micromagnets
• Hydrodynamics of the electronic Fermi liquid: a pedagogical overview
• Superballistic paradox in electron fluids: Evidence of tomographic transport
• Wiedemann-Franz law violation domain for graphene and nonrelativistic systems
• Lorenz ratios of diagonal and Hall conductivities in a Dirac electron liquid
• On the Wiedemann-Franz law violation in Graphene and quark-gluon plasma systems
• Quantum transport of Dirac fermions in selected graphene nanosystems away from the charge-neutrality point
• Sub-Sharvin conductance and incoherent shot-noise in graphene disks at magnetic field
• Mott and Wiedemann Franz Law for Monolayer Graphene for Different Scattering Mechanisms
• Charge and energy transport in graphene with smooth finite-range disorder
• Strain-Induced Half-Metallicity and Giant Wiedemann-Franz Violation in Monolayer NiI${}_2$