Crossno, Jesse DylanShi, JingWang, KeLiu, XiaomengHarzheim, AchimLucas, Andrew JamesSachdev, SubirKim, PhilipTaniguchi, T.Watanabe, K.Ohki, T. A.Fong, K. C.2016-06-102016Crossno, J., J. K. Shi, K. Wang, X. Liu, A. Harzheim, A. Lucas, S. Sachdev, et al. 2016. “Observation of the Dirac Fluid and the Breakdown of the Wiedemann-Franz Law in Graphene.” Science 351 (6277) (February 11): 1058–1061. doi:10.1126/science.aad0343.0036-8075http://nrs.harvard.edu/urn-3:HUL.InstRepos:27303654Interactions between particles in quantum many-body systems can lead to collective behavior described by hydrodynamics. One such system is the electron-hole plasma in graphene near the charge neutrality point which can form a strongly coupled Dirac fluid. This charge neutral plasma of quasi-relativistic fermions is expected to exhibit a substantial enhancement of the thermal conductivity, due to decoupling of charge and heat currents within hydrodynamics. Employing high sensitivity Johnson noise thermometry, we report the breakdown of the Wiedemann-Franz law in graphene, with a thermal conductivity an order of magnitude larger than the value predicted by Fermi liquid theory. This result is a signature of the Dirac fluid, and constitutes direct evidence of collective motion in a quantum electronic fluid.en-USJournal Article2016-06-1010.1126/science.aad0343