Johnson noise thermometry reveals the Dirac fluid in graphene

Near the charge neutrality point in graphene, the Fermi surface vanishes leading to the formation of a strongly-interacting quasi-relativistic electron-hole plasma, known as a Dirac fluid. These non-Fermi liquids share many features with quantum critical systems including a fast electron-electron scattering rate which makes them well suited to hydrodynamic descriptions. A number of exotic properties have been predicted including a diverging thermal conductivity resulting in the breakdown of the Wiedemann-Franz (WF) law. I will discuss the experimental technique---based on Johnson noise thermometry---used to measure the electronic thermal conductivity of graphene and probe the unique transport dynamics of the Dirac fluid.