title: Observation of the Dirac fluid and the breakdown of the Wiedemann-Franz law in graphene.
abstract: Interactions 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, thanks to decoupling of charge and heat currents within hydrodynamics. Employing high-sensitivity Johnson noise thermometry, we report an order of magnitude increase in the thermal conductivity and the breakdown of the Wiedemann-Franz law in the thermally populated charge-neutral plasma in graphene. This result is a signature of the Dirac fluid and constitutes direct evidence of collective motion in a quantum electronic fluid.
authors.affiliation: Department of Physics, Harvard University, Cambridge, MA 02138, USA. John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA.
authors.forename: Jesse
authors.initials: J
authors.lastname: Crossno
authors.affiliation: Department of Physics, Harvard University, Cambridge, MA 02138, USA.
authors.forename: Jing K
authors.initials: JK
authors.lastname: Shi
authors.affiliation: Department of Physics, Harvard University, Cambridge, MA 02138, USA.
authors.forename: Ke
authors.initials: K
authors.lastname: Wang
authors.affiliation: Department of Physics, Harvard University, Cambridge, MA 02138, USA.
authors.forename: Xiaomeng
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Physics, Harvard University, Cambridge, MA 02138, USA.
authors.forename: Achim
authors.initials: A
authors.lastname: Harzheim
authors.affiliation: Department of Physics, Harvard University, Cambridge, MA 02138, USA.
authors.forename: Andrew
authors.initials: A
authors.lastname: Lucas
authors.affiliation: Department of Physics, Harvard University, Cambridge, MA 02138, USA. Perimeter Institute for Theoretical Physics, Waterloo, Ontario N2L 2Y5, Canada.
authors.forename: Subir
authors.initials: S
authors.lastname: Sachdev
authors.affiliation: Department of Physics, Harvard University, Cambridge, MA 02138, USA. John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA. pkim@physics.harvard.edu kc.fong@bbn.com.
authors.forename: Philip
authors.initials: P
authors.lastname: Kim
authors.affiliation: National Institute for Materials Science, Namiki 1-1, Tsukuba, Ibaraki 305-0044, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Taniguchi
authors.affiliation: National Institute for Materials Science, Namiki 1-1, Tsukuba, Ibaraki 305-0044, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Watanabe
authors.affiliation: Quantum Information Processing Group, Raytheon BBN Technologies, Cambridge, MA 02138, USA.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Ohki
authors.affiliation: Quantum Information Processing Group, Raytheon BBN Technologies, Cambridge, MA 02138, USA. pkim@physics.harvard.edu kc.fong@bbn.com.
authors.forename: Kin Chung
authors.initials: KC
authors.lastname: Fong